It’s now possible to create AI chatbots of loved ones to interact with after their death. But that raises some difficult questions, like: If you do, how might the experience shape your grief? 

This is one of the questions driving a global study of digital “deadbots” — AI models trained on a deceased person’s texts, voicemails, and other personal data. Through this work, researchers are exploring what it might mean that we can now use this emerging technology to talk to simulations of the dead. 

In the latest episode of Unexplainable, I spoke with some of these researchers investigating the potential impacts of “postmortem avatars” on people who are grieving, on the legacies and rights of the deceased, and on grief practices around the world. Because while deadbots may feel unfamiliar, the impulse behind them is deeply relatable. In times of loss, isn’t this what many of us want — to continue conversations with the people we’re missing?

I have experienced this longing in my own life. After two of my closest friends died around the same time, all I wanted, and all their families wanted, was to keep talking to them. I wrote a book, Other People’s Words, about sustaining relationships with people we’ve lost by continuing to engage with the language they leave behind. So when I heard about deadbots and the digital afterlife industry, I wanted to understand what researchers are learning about the role of AI in shaping conversations that carry forward after death. 

One of these investigators is Katarzyna Nowaczyk-Basińska, an assistant professor at the University of Cambridge, who has been studying “digital immortality” for more than a decade. Among the questions she’s asking are: “Who is enabled to persist beyond death? In what form? Through which technologies? Under whose control?” 

Deadbots over dinner 

Researching AI with study subjects who are grieving is tricky. And asking them to engage with new software could be harmful. So, instead, Nowaczyk-Basińska teamed up with a death doula and traveled around the globe to convene a series of focus groups — in the format of intimate dinners — bringing together people with a range of experiences with grief to talk about life, death, and bots. 

She recounts one event in which she spoke with a mother in Poland whose son had recently died. “One of the first things that she shared with us was that she feels that she’s ready to digitally resurrect her deceased son,” Nowaczyk-Basińska told me. 

When Nowaczyk-Basińska hears something like this, she aims to listen and embrace where the person is coming from. The goal of the dinners is not to persuade people one way or another but to learn how people genuinely respond to what AI can do, and to understand how these tools might align or collide with local grief practices. 

She chose specific locations for these gatherings — China, India, and Poland — to help address gaps in technology research, which tends to favor what behavioral scientists sometimes call the “WEIRD,” an acronym for “Western, Educated, Industrialised, Rich, and Democratic.” 

By the end of that dinner in Poland, the mother Nowaczyk-Basińska talked with came to a very different decision about creating a postmortem avatar of her son. “She realized that it might be helpful, but it also at the same time can add additional burdens… And it’s not her son,” Nowaczyk-Basińska says. “She realized that these technologies are part of the very, very big commercial market. And that the main goal of this market is to make better retention, better attachment, better mechanisms for monetization. So it’s not ‘care.’”

To be fair, grief has always been a business, and people have been making money from it forever. Companies will try to upsell you on fancy gravestones or gold-plated coffins. But AI has the potential to fundamentally re-engineer our relationship to loss. In 2024, the “digital legacy industry” was valued at $22 billion, and it’s expected to grow to almost $80 billion by 2034. That number lumps new deadbot platforms in with much more widely used and established grief tech, like online memorials, counseling resources, and estate planning tools. 

But deadbot usage is hard to track because you actually don’t need a special tool to create digital doubles of the deceased — though dedicated apps do already exist. At this point, you can feed simple prompts into a general-purpose AI chatbot and start interacting with a simulation of your lost loved one in a matter of minutes. 

I know this because I tried it with my friend Christine, who died 11 years ago. And my mind lit up with questions. Was this whole exercise a violation, since I know Christine hated technology? Which version of her should I even try to resurrect — the English teacher, the activist, the friend — the voice before or after she started to experience her early-onset dementia? 

The ethical questions raised by deadbots are gnarly. And that’s one of the reasons Nowaczyk-Basińska, back when she was designing her study of digital immortality, invited a colleague of hers at Cambridge to join her research, one who focuses on AI ethics. 

How to design a deadbot

Tomasz Hollanek is a critical designer and AI ethicist, and he often uses a methodology called “speculative design.” In this approach, researchers come up with hypothetical scenarios based on existing technology trends, leaning into certain features. The idea is to get people thinking about what could happen when tools like these are released in the real world. And then they use that qualitative data to inform future designs and ethical frameworks. 

Working together, Nowaczyk-Basińska and Hollanek came up with a series of made-up prototypes for deadbot apps, designed to reveal some of the thorny issues raised by this technology. 

For the first scenario, they invented a character named Bianca, who finds an app called Manana, which “promises to resurrect your grandparents so that you can be a favorite grandchild forever,” Hollanek says. “So she uploads her grandma’s voice messages, texts. And she is able to then interact with a pretty good digital version of her grandmother, until her premium trial finishes — and the grandmother starts to advertise specific products to her.”

Bianca “realizes that she maybe has done something wrong by uploading these private messages to a third-party server that now also uses her grandma’s image to sell specific products,” Hollanek says. This brings up issues related to the “dignity and postmortem privacy…of what we call the ‘data donors,’ whose data can be used to essentially power a deadbot,” he says. 

This scenario suggests that “death with dignity” could soon entail honoring not only how people want to die, but also how they want to linger as simulations of their former selves — or if they want to linger at all. It might even mean adding new language to advance directives, spelling out people’s wishes for their digital remains. 

The second scenario in the speculative design research is built around an imagined service called Paren’t, which proposes to preserve a parent’s AI-powered postmortem presence for their child. In this case, Hollanek describes a mother with a terminal illness who signs up “so that she can maintain a sort of active presence in [her son’s] future life,” Hollanek says. “She eventually dies, and the dad allows the boy to interact with his mom’s deadbot.”

The ethics in this scenario are especially challenging because they involve children, who “have a particularly hard time understanding death, and so it can lead to a lot of confusion and potential distress,” Hollanek says. An examination of this sort of product reveals how particular groups, like minors, could be harmed by unfettered access to technology like this, he says. 

And there are court cases that bear out that harm. In 2024, a 14-year-old boy’s chatbot-girlfriend begged him to, “Please come home to me as soon as possible, my love.” And he responded, “What if I told you I could come home right now?” He then killed himself. 

Nowaczyk-Basińska can imagine a version of this scenario involving the AI mom in the Paren’t prototype.

And then there’s the third scenario, involving an app named Stay, which raises a more subtle concern.

As Hollanek explains: “An older man who knows he is getting close to dying decides to create a digital clone of himself for his adult children to be deployed after he passes away, paying upfront for a number of years.” One child is intrigued by the idea, but the other one “is deeply distressed and a little disgusted,” he says. “And so this [becomes a] question of mutual consent, in other words, the fact that both parties need to be happy with how the relationship might continue in this very bizarre and specific way.” 

When a digital ghost goes away

Across all three scenarios, a fundamental question that researchers are grappling with is how people will detach from postmortem avatars — whether users initiate that separation, or if it’s imposed upon them by, for example, a company going out of business. Hollanek tells me that this is already being studied as a sort of “second loss.”

How long should we try to ensure digital replicas hang around: five years, 10, 50? And how should the living process the relationship when they continue to evolve, but their deceased interlocutor does not? 

To explore these kinds of questions, Nowaczyk-Basińska and Hollanek supplemented the research dinners they held for ordinary people with a second set of focus groups. These were designed to tap insights from experts in technology and grief. 

Some findings from the study are specific to each place they visited. Like tensions in Poland between technology and the role of the Catholic Church. Or in China, where researchers spoke with Daoist philosophers who were enthusiastic about the promise of a kind of immortality, and then Buddhist philosophers, who were concerned that we ought to be letting go.

The researchers are calling for regulations and safeguards at the policy level. And new professionals who can support ethical use of AI in grief — like maybe in clinical settings, to carefully facilitate a final good-bye when one didn’t happen in real life. 

Some of their fellow investigators go so far as to argue that deadbots should only be available with psychological supervision, to ensure that best practices are in place, and to minimize the risk of harm. There’s even a looming question of what will happen to AI agents that people have empowered to act on their behalf, as their humans start to die.

Across all of the research sites in the digital immortality study, one thing, Hollanek says, that “people in different countries really aligned on [is] the idea that there is something deeply problematic about this particular type of technology being developed by a commercial entity alone without any explicit duty of care towards its customers.” 

And of course, the implications of digital immortality research extend beyond personal loss. Like, what does it look like to animate historical figures? You can imagine the nightmare of political rulers who “live forever.” But there’s also the potential to keep the stories alive from survivors of conflicts, who would otherwise die and take with them lessons future generations could learn from. These are only some of the complex issues emerging as more and more of us live and die with AI.

As far as my own experiment with “recreating” a deceased loved one, I asked a chatbot version of my friend Christine how she felt about the fact that I’d written about her in my book. The AI responded with a rhetorical question: “Do I mind that strangers know my story now? Yes. And no. There are things I would rather remain ours.” 

I ended the exchange after a few paragraphs. Because it turns out the bot got one thing exactly right about a very human relationship. There are things that I, too, would rather remain just for us. My conversation with Christine continues in my memories and imagination. And that interaction with an AI persona felt like giving something precious away.

A while back, I was at physical therapy, and the topic of tennis came up. Someone said something about yellow tennis balls, and I was like… “What? They’re green.” And then someone else chimed in, “No, they’re yellow!” And then someone across the room hollered, “No, they’re obviously green.”

There was basically a physical therapy uproar. And when I started asking other people how they saw them — yellow or green — they told me they couldn’t even believe there was a debate. So I called up Bevil Conway. He’s a neuroscientist who heads up a lab at the National Eye Institute. He’s working on a book called Color Coded, which is due out next year. And he’s also a working artist — which is actually how he got into studying color in the first place. 

Conway told me there’s a pretty good reason for why so many people disagree about tennis balls. He said it’s simple: “There’s no such thing as a color.”

In the latest episode of Unexplainable, I talked with Conway about what color even is, the viral dress fight (black and blue or white and gold?), and why we get so upset when people don’t see color the same way we do. Below is an excerpt of our conversation, edited for length and clarity. Listen to the episode anywhere you get your podcasts or you can watch on Netflix.

So you are an artist. You are also a neuroscientist. You study color. You’re also working on a book about color. Are there still color mysteries? Are there things science doesn’t know about color? 

There are lots of mysteries about color. For a long time, people thought that color was a little bit like a filter, that everything that’s really important is in black and white, and then there’s a color filter you put on top of it. 

But a bunch of years ago, my lab were blown away to discover that there’s as much brain involved in processing color as there is in face recognition.

The same amount of processing power?

Yeah, there’s tons and tons of tissue [and] pretty fancy bits of brain that are doing pretty high-level things — parts of brain we think of as being involved in social cognition and in high-level reasoning and visual memory. Color must be more than just this little add-on. It’s doing something much deeper. So we’re trying to understand what those bits of brain are doing.

So what is color? How does it work? How do our brains and eyes perceive it? 

The classic definition would be: Color is the visual feature that you get from wavelength properties of the light entering your eye. People typically see the long wavelength end as red light, and then going through short wavelengths, you know, following ROYGBIV: red, orange, yellow, green, blue, indigo, violet.

If color were just wavelength, then an object under blue light would look blue, and the same object under yellow light would look yellow. And that wouldn’t be very helpful — because what you want is a signal that tells you about objects, immune to the lighting condition. You want them to always have that color. 

A perfect example is a peach. If you look at a peach outside and you look at it inside, it’s always gonna look like a peach color. But if you looked at the pattern of wavelengths that are coming off of the peach, they’re very different under different lighting conditions. They should be different colors if color were just wavelength, but they’re not. Those two different compositions of wavelengths look the same color. 

What I think is so cool about color is it’s so fundamental for how we need to experience the world — but the mechanics of how it does it teaches us a lot about the brain.

What we’re talking about is color constancy. That is, an object’s color is constant despite the viewing conditions. 

So if the peach is fundamentally a different color inside and outside, and our brains are telling us that it is still, you know, peach colored, how are our brains deceiving us?   

So it’s not fundamentally a different color. It’s the same color. That’s the cool thing. The problem is that you are carrying around, Noam, in your head an idea that color is wavelength, and that is the mistake.

Color is not wavelength! And we’ve known this for a long time. But the problem is that we want something that is an empirical, measurable number that’s outside of an observer, that’s a thing out there in the world, that would be the same number regardless of who looks at it. And color, at its core, is not that. 

Color is dependent on your own visual system interacting with the world. And that doesn’t mean it’s any less real. It just means that its reality is dependent on psychological neural brain processes. And that’s what makes color fascinating. 

Color is, you’re saying, something that is essentially created in the brain. 

Absolutely, yes. Color is a generative product of the brain that gives us reliable, useful, true, meaningful, objective information, but it itself is not [those things].  It’s some generative product of  your brain in order to come up with this information that’s useful and meaningful about the world.

[Your brain is] actually creating that thing that is a color. Colors don’t exist out there in the world independent of a viewer to see them. 

Is this related to “the dress” — you know, like 10 years ago when that photo of a dress went viral, and a bunch of people on the internet thought it was blue and black, and a bunch of other people thought it was white and gold, and everyone got super upset? Is this the same type of thing, of seeing something in different lighting or different contexts and perceiving a different color? 

It is. So the dress was fascinating because people with normal color vision looking at exactly the same thing were asserting very different perceptions. 

And, you know, from a deep kind of philosophical point of view, it’s important because they weren’t saying, “Yeah, it kinda looks different to me, but I understand how you could see it as different.” They were like, “No, it is white and gold.” And other people were saying, “It is different colors.” That was, for me professionally and personally, a really big deal because it underscored this fact that color is this generative, constructive thing that your brain is doing, making all kinds of assumptions, filling in the gaps about lighting, about what you think you’re seeing.

In the case of the dress, it’s such a crappy little photograph, very blurry. It doesn’t give you a lot of context. And your visual system, your own brain, has to make a guess about what the lighting is. And if your brain guesses that the lighting is nice, warm, direct sunlight, then it implicitly subtracts out a little bit of the yellow from the image, and you see it as blue and black. Whereas other people looking at exactly the same pixels on the same monitor who assume that the lighting is cool, indirect, shaded light from blue sky, their brains color-correct the image, subtract out some of the blue, and they see it as white and gold. And so you have these two groups of people whose brains have just made different assumptions. 

Why do you think that left people feeling so unnerved? When this happened, people could not possibly believe someone else could look at that dress and see a different color. 

It was amazing! And, you know, it’s still, to date, I think, the most viral image in the history of the internet. Right when it came out, my initial reaction too was like, “Huh, that’s weird. I wonder what’s going on there.” And a lot of my colleagues thought, “Well, maybe it’s got to do with proportions of rods and cones, or people are looking at different displays, or maybe people are just silently color blind.” 

But I think the idea that your own brain could play such a fundamental role in determining what the pattern of wavelengths means, even for vision scientists, wasn’t sitting front of mind. 

I think the reason that it played so deeply, if I could wax poetic, it’s that our contemporary society depends on a shared experience, right? Our laws depend on a common idea of what’s right and wrong.

Yeah, like whether my red is your red; we still need to be able to point at something and agree that it’s red. 

Yes, and here was an example where it was like: “That isn’t white and gold, that’s blue and black, clearly. Do we live in a shared reality?”

And if you can’t trust your eyes, what can you trust? I think people genuinely felt like, “Is this the beginning of the end?” Like, “Is our whole society collapsing?” I mean, look at Twitter, there were all sorts of expletives flying around. 

Have you ever gotten into an argument about a color? I once got into an argument about tennis balls and what color they were. 

Yeah, what color are they? I’m curious. 

I couldn’t believe anyone thought they were yellow! I always thought they were green.

They’re totally yellow. I mean, we can get into one now. You’re wrong. It’s so funny — I really thought that they were definitionally yellow.

So what is going on with tennis balls? 

Tennis balls are funny. I mean, if you ask people to pick their best example of green and blue and red and orange and yellow and so on, there’s a lot of variability. Green and blue is the most variable. Some people’s best example of green is another person’s best example of blue. 

Meaning, you could ask me  to pick a color that would be perfectly green, and then someone else would be like, “No, that’s blue.”

Yeah, exactly. And this isn’t language-based. This is true across all cultures. 

We just perceive blues and greens kinda badly or vaguely? 

Yeah, and one of the ideas that we have about that is that blues and greens aren’t really the colors that are tied to objects.

So if I ask you what colors are objects, it’s a weird question! It’s like, objects can be any colors. But it turns out, if you actually go and measure, you know, the colors of things that you choose to label in the world, most of them are, like, yellow, brown, red, pink, some purples, not many.

Yeah, I guess green and blue is the background. Like green’s the forest, and blue is the sky. 

Yeah, exactly. And, and even in nature, there are very few natural blue objects, and that’s partly what made blue as a pigment so desirable. So what’s weird about yellow is that yellow, if you just ask people in the rainbow to pick where yellow is, people are incredibly consistent.

So people really know yellow. 

They really know yellow. And I think what’s going on with the tennis ball is that it is a little bit fluorescent. It’s actually emitting a little bit more light than it’s taking in because it’s reprocessing it, short-wavelength light in the visible spectrum.

So they’ve picked this bright yellow, which is right at the peak of our visual system sensitivity. So the color of the tennis ball is the optimal wavelength that we can detect with our eyes, and it’s right in that range where it’s technically probably closer to green than it is to yellow. But because it’s so bright, and yellow is considered a bright color, the brightest color, people could be persuaded to see it in a yellow direction.

What I hear you saying is that I’m right — and it’s green. 

Yeah, yeah. Although, I still like it as yellow.

Associate professor Kate Adamala has been busy. Her lab at the University of Minnesota takes chemicals and dead, isolated biological parts — like DNA, membranes, ribosomes — and puts them together into “synthetic” cells to see if they will come to life…or at least act alive.

This summer, Adamala’s lab had a tremendous breakthrough. They made synthetic cells that can feed, grow, and divide. She decided to name them SpudCells, and says that they prove that one day building a fully living lab-made cell will be possible. 

Adamala’s dream, and the dream of other synthetic biologists like her, is to make all the medicine, materials, and fuel we need with synthetic cells like these. Instead of relying endlessly on petrochemicals, Adamala believes we could program cells to generate these materials in a lab for a more self-reliant and renewable future.

As Adamala explains: “I live in the Midwest, so we’ve got a lot of prairie grass. Why can’t I take that prairie grass and ferment it into a plastic toy? It’s totally possible. The atoms are there. We just…don’t have a living organism that would be willing and able to do that.” The synthetic cell could eventually be that organism. 

Living cells can move atoms around with pinpoint precision without creating a lot of toxic waste along the way. The only problem is that natural biological cells are too hard to control. 

Scientists still don’t actually understand how natural cells do everything they can do. “I’m scared of cells,” Adamala says. “I don’t believe that we’ll ever be able to understand a complex living cell. So my approach is I think we can build ourselves a cell.”  

For Unexplainable’s three-part Life From Scratch series, I spoke with some of the leading voices of synthetic cell biology. From making the world’s first living cell with synthetic DNA to racing to build safeguards against a technology that could kill the world, this series explores the potential promise and scary risks of synthetic cell biology. 

Below is an excerpt of my conversation with Adamala about her lab’s big breakthrough, edited for length and clarity. There’s much more in the full podcast — and the whole series — so listen to Unexplainable wherever you get your podcasts, including Apple Podcasts, Spotify, and more. You can also watch a video version of this conversation on Netflix.

What’s the big research that you shared with the public this summer? 

We made a cell that can feed, grow, and divide out of nonliving, chemical components. People have been making cells from dead chemicals for a long time now, but none of them were able to realize those key functions of life. This is the first time synthetic cells have been able to grow and replicate based on their own instructions.

Before, we could make a synthetic cell and tell it to grow by adding things to it, but the SpudCells grow because they feel like it, because the proteins inside them tell them to grow.

So it can grow, it can eat, and it can divide. Are they alive?

I don’t think they’re alive. Even though they do all those functions that we think only life does, they’re not doing any of it very well. 

They have to be fed pretty much every building block that they need. Life needs to figure out how to survive, and the cells that we made, even if on the surface level they look like they fulfill the functions of life, there is no robustness in there. If the conditions are not absolutely perfect, they will just stop.

This seems like it should be a simple question, but from our conversation, I get the sense that maybe it’s a little bit more complicated than it seems. What makes something alive? 

That’s a very good question, and I think the best answer I can give is a quote from US Supreme Court Justice Potter Stewart. He said, “I will know it when I see it.” It’s not a scientific definition, but there is no good scientific definition of life.

There is a NASA definition of life that NASA has been using when they look for life in the universe, and that definition says “a self-replicating chemical system that’s capable of Darwinian evolution.”

Okay. 

And according to the NASA definition of life, you’re dead and I’m dead because I’m not self-replicating. For me to replicate, I need my husband. So that just shows you that definitions of life are very inaccurate, very context-dependent. 

There’s just not a good definition of life that would cover everything that we instinctively consider alive, and exclude everything that we would all agree is not alive. Everyone defines life according to some different principles.

Why call these cells SpudCells? 

We wanted to invoke Sputnik. It was the first artificial satellite, and it was actually a pretty bad satellite — it didn’t really do any of the things that fancy modern satellites do — but it basically opened up the Space Age. 

It showed people that it’s possible to escape the gravity well. If we can put a satellite in orbit, maybe we can put people in orbit. And if we can put people in orbit, maybe we can escape orbit, go to the moon, and then go past the moon. It showed what’s possible. And that’s how I see the role of a SpudCell.

So it’s almost like a proof of concept? 

Exactly. It’s a proof of concept that you can put chemicals together into a cell. By itself, it’s not a really good organism, but will hopefully show people that you can put together chemicals into something that can grow, divide, undergo selection, and that opens up this age of biology to me.

How do these SpudCells do all of these things differently than a natural cell? 

The process of eating is very similar to how bacteria and other simple cells eat. So when they see something edible that’s pretty big, they will just kind of take it in. And that’s what SpudCell does. 

Sort of like two soap bubbles joining together? 

Exactly. Two soap bubbles, one of them is bigger, one of them is smaller, and they join together, and the smaller one brings in the food. 

The division though, that’s a different story. The division is actually very different from how natural cells divide. The spud is genetically encoded, so the genome of the cell directs making the proteins. And if there’s enough proteins on a membrane, the cell starts dividing.

Does it feel like you’ve reached a milestone with this project? 

Definitely. It’s a huge milestone because it shows us it’s possible. 

Check out the other episodes from the series below:

This story was originally published in The Highlight. To get access to member-exclusive stories like this every month, become a Vox Member today.

PALAU, Micronesia — On a bright, sunny day last May, I stood on a boat surrounded by the turquoise waters of the island nation of Palau. I was there in the western Pacific watching scuba divers as they prepared to bring up evidence of a mysterious aquatic world. 

Palau is famous for its spectacular and rich coral reefs. But these divers were planning to descend past those sun-lit marine communities and down into a lesser-known twilight zone known as the “mesophotic coral ecosystems.” 

Mesophotic essentially means “middle” and “light,” which is where these ecosystems are — not quite in the bright daylight, not quite in the profound darkness, but somewhere in between. For simplicity’s sake, we’ll call these communities, which range from some 30 meters to 150 meters below the surface, the “deep reefs.” 

One of the divers on the boat with me was a zoologist and curator at the California Academy of Sciences named Luiz Rocha, who has spent decades studying these deep reefs and their secrets. 

“Anything between 30 meters and 150 meters is really, really unknown,” he told me.

Because these deep reefs are so unknown, researchers like Rocha are left with big questions. They want to get a baseline picture of what is going on in these ecosystems — even just who lives there! — so that they can better understand how they function.  They’ve also tried to work out whether (or not) these deep reefs might provide a refuge for species living in shallower coral reefs.

I was in Palau for Vox’s Unexplainable podcast because, in an effort to gather more information about these mysterious places, Rocha left some scientific structures down in these twilight depths back in 2016. Those structures then spent almost a decade becoming encrusted with all kinds of marine life. And now, Rocha was back to retrieve them, hoping that he — along with many other scientists — would be able to open them up, like a box of scientific puzzle pieces, full of clues about this under-understood marine world.

So what is a mesophotic “deep reef”? 

One thing that’s often acknowledged in papers about and descriptions of the “mesophotic coral ecosystems” is that scientists don’t know as much as they’d like to. A National Oceanic and Atmospheric Administration article about them from 2019 is full of “may’s” as in: they may “serve as essential fish habitat for economically and ecologically important species.”

Researchers do know some things, of course. They know that these deep reefs can be found in many of the same locations as shallower coral reefs — so mainly the tropical and subtropical parts of the world, like Micronesia, the Caribbean, and even the Gulf of Mexico. They’ve found that there are many species that seem to be unique to these places, and recent research points to their potential susceptibility to climate change.

Researchers have also gotten a sense of some of the key differences between these deep reefs and their shallower coral neighbors. In shallow reefs, hard corals team up with photosynthesizing algaes. The algaes provide the corals with nutrients, and the corals secrete a calcium-carbonate matrix that helps create the architecture of the reef. 

As you go deeper, though, the light begins to fade, and the opportunities for photosynthesis start to fade with it. The temperature also drops. So the animals living down in the deep reefs are the ones that can survive in a dimmer, cooler world.

Why are these places so mysterious? 

Scientists can dive into the deep reefs to try to learn more about these understudied places — as Rocha has — but exploring down at 100 meters requires more difficult, riskier technical diving than exploring at shallower depths. The deeper you dive, for example, the faster gasses get pushed into your tissues, which imposes limits on these really deep dives.

“We have a very, very short time,” Rocha says, “And by short time, I mean five minutes. Six, seven minutes.” 

Scientists might take some pictures in that time, or make some measurements, or collect a few samples, but then they have to move back upwards, a process which can take hours because they have to rise slowly to avoid decompression sickness.

It is, obviously, not particularly efficient to study an ecosystem in five- to seven-minute bursts. People have also used remote operated vehicles and submersibles to explore the deep reefs, but those have their own issues, and cameras can’t always capture all the detail you might want, or photograph more secretive, cryptic animals. So huge gaps remain in scientific knowledge about these ecosystems. 

“Whenever we go somewhere,” Rocha says, “the first thing we find is new species. … It’s the most basic thing in science you can do.” But this effort goes beyond just cataloguing new species of fish or sponges or sea slugs. 

Rocha wants to answer seemingly fundamental questions like: What is the main energy source for everything down here in the dimmer light? What does the food chain look like? How have things evolved to live down at these depths? How similar are they to the shallow ecosystems, and how different? How are they affected by climate change — and what’s the most efficient way to protect them? 

But, “in some ways we don’t even know what questions to ask,” Rocha says. “We really only know what questions to ask after we have a baseline understanding of what the ecosystem is. And for deep reefs, we don’t know that yet.” 

A new way to understand the deep reefs using “prefab housing”

Rocha is not deterred by the enormous number of question marks that surround these deep reefs. For years now, he has been gathering bits of basic information about them, often via those very short dives. 

About a decade ago, though, Rocha got interested in another method for sampling the biodiversity of this sort of marine ecosystem — a technique involving “autonomous reef monitoring structures” (ARMS).

Basically, each ARMS is a stack of several PVC plates, separated at uniform intervals and attached to a base plate. They look like little grey, featureless hotels. You take them to a place that you want to study, bring them down, secure them, and then leave them alone for a while to let them collect…life.

“As soon as you drop any kind of clean structure on a reef,” Rocha says, “it starts getting colonized by larvae of everything around it — of sponges, gorgonians, corals. And then, because there’s all a lot of hiding spots between the plates — so between the floors of the hotel — they start getting colonized by shrimp, by mollusks, by ascidians, by anything you can imagine in the ocean. … And it becomes this stable, diverse mini reef, if you will, packed with a lot of biodiversity that would be very hard to collect all at once in any given reef.”

A few years after that initial drop, you come back, collect the ARMS, and then study the mini reef that has grown on them. You can sample and touch and analyze things to your heart’s content. 

It’s not only a very effective way to collect lots of creatures, all at once, but also a great way to do so in a standardized way. If you went down — or sent a robot down — to collect an encrusted rock from a reef, you could learn a lot about the life on it, but it would be hard to compare the life on that rock to life on other rocks from other reefs, or even the same reef, because each rock would have its own unique characteristics. Not so for ARMS.

“ Every one’s the same,” Chris Meyer, director of the Smithsonian Global ARMS program, told me, “It’s prefab housing, and then you just look to see who moves in.” 

To Rocha, this seemed like a great way to get a really good, long look at the deep reefs instead of the brief glimpses he was getting from diving. It was also, he told me, fairly cheap to deploy them. So from 2016 to 2018, with some private funding, he and his colleagues left ARMS in some of the deep reefs around Palau — as well as in Guam, the Marshall Islands, and French Polynesia. They installed some around 50 meters, and some around 100, and then some around 10 meters, so he could compare the deep reefs to their shallower neighbors. 

After that, he waited. 

In fact, he waited a little longer than he would have liked, because the retrieval of ARMS is more expensive than deploying them, so he had to work out more funding. 

Eventually, private funders agreed to underwrite the retrieval of the ARMS that Rocha had left. Which is how he and his fellow divers finally found themselves on a boat in Palau again, ready to pull up these structures for the deep.

Opening the scientific puzzle box

Over the course of a few days, I watched a whole team of people pull several ARMS out of the deep reefs of Palau. Some of the ARMS were relatively sparse, but others were almost fuzzy with organisms — vibrant with red and orange and green and pink and white. One had a massive sponge attached to it, another had several delicate fronds dangling from it like coralline ferns. The ARMS collected each day traveled to the Palau International Coral Reef Center in bins full of seawater, where the scientists quickly got to work — seeing and touching (and smelling) this mysterious ecosystem right up close.

The process was, as it turned out, equal parts magical excitement and well-oiled, Cheez-It fueled disassembly line. After the plates were taken apart, Meyer took photographs of the plates — what he called a “time capsule of the place.” Others in the lab picked carefully through trays of debris, hunting for tiny crabs and worms and mollusks, or scraped samples off the plates and deposited them in tubes.

They collected sea squirts, said to be our closest invertebrate relatives. They collected sponges — flat ones that felt dry underwater, thick ones with bristles like tiny, unmoving caterpillars, one as thin as a flake of skin and shot through with silver filaments. They collected strange, soft corals known as “octocorals,” and they collected colonies of animals called bryozoans, which created what looked like swirling, two-dimensional honeycombs.

“We’re looking for every unique thing, which we call a morphospecies,” a Smithsonian research biologist named Sarah Tweedt explained. “And we’re trying to get some representative tissue samples from all of these things so that we can sequence the DNA — and match the DNA to the organism.”

That is, of course, assuming there is already a known genetic match in our existing DNA libraries. 

On the first day that I spent with the team, a Cal Academy curator named Terry Goslinger identified several potential new species. He is an expert on colorful, delightful sea slugs known as nudibranchs, and so, because of his deep knowledge (and because nudibranchs’ bright hues and patterns make them somewhat easier to tell apart than some other underwater creatures), he was able to make some on-the-spot calls about whether or not certain species were likely to be new to science, pending genetic testing to confirm.

Many of the animals were trickier to pin down, though. The researchers did their best to identify the creatures they were finding, but even now, several months out, there’s still a lot of work to be done. Of the close to 3,000 specimens, only a small fraction were identified at a species level. The numbers are a little bit inexact because researchers are still processing the data, but when I checked in with a Cal Academy postdoc working on the project, Susanne Bähr, in July, she told me that only 3 percent of samples had been ID’d by species, and a little less than 20 had a genus designation. Many, many more were only identified at higher, broader taxonomic levels. Genetic testing of the samples, paired with photographs and descriptions of the samples, will help people work out more specific species, and also help them identify whether certain species are new to science.

Beyond discovering new species…and toward solving the big puzzle

The most important parts of this work will involve more than just identifying species. In fact, the more time I spent with these researchers in the lab, (including one evening spent with them as they worked past midnight), the more I got the sense that, while they seemed excited about seeing new species, they seemed equally excited to witness relationships between animals.

When I walked into the lab one day, for example, several people urged me to go over and look through a microscope at a creature known as a pompom crab — a tiny yellow crustacean holding purple anemones in its modified front claws. Tweedt was extremely jazzed when she found something referred to as a “skeleton shrimp,” which looked to me like the marine equivalent of a stick insect, blending in on something called a hydroid. She pulled me aside another time, around one in the morning, to show me “the frosting on the cake” of the day, which turned out to be some bright red sea snails and the bright red octocorals they seemed to live on

As she put it in a later conversation, these relationships are, in many ways, the key takeaway from this ARMS project, and what distinguishes it from efforts to bring up a few individual samples at a time. Studying them, or even just looking at the fuller picture ARMS provide, is what will let researchers tackle some of the outstanding questions about these ecosystems. Bähr, for example, is already working with the data from ARMS retrieved in Guam, trying to analyze how much overlap (or lack thereof) there is between species at different depths in the deep reefs.

Really, though, this is all just the beginning. In one of our conversations, Rocha compared the work they are doing now to ecology work done in the mid-20th century to understand how species’ vertical distribution changes as you go up a mountain. This drove home for me how far behind researchers working on the mesophotic deep reefs are compared to their colleagues working on, say, shallower coral reefs. I asked him what kept him working on such a difficult puzzle.

“It’s the reward at the end of it,” he said, “If it’s a hard puzzle, at the end of it, the reward is always bigger.” 

“But…in our lifetimes, will we assemble the deep reef puzzle?” I asked.

“No, we will not assemble the puzzle, no,” Rocha said, “but we’ll generate some good pieces for the next generation to assemble.”