One morning early in our acquaintance I came out to find Taslan Poplar in t-shirt and drawstring trousers, practicing a kata in the clearing in front of the house, moving with a fluidity I would not have expected. I squatted down with my tea to watch. After about twenty minutes he mounted the engawa and squatted down beside me. We talked about how good it was to be there: the quiet, the cool, clean air, how humbling it was—this was Taslan’s word—they’d been able to regrow the forest, or grow a new one, since in the old days you’d never find cypress and gum in the same place, something about mycorrhizal diversity, and how it was essential, at this stage, to bring everyone together in a place like this. I asked him was this place his and he said no, just a place he borrowed from time to time.

We went in to find the others getting up: making coffee, negotiating an unfamiliar space with unfamiliar bodies. We were there that weekend to plan a raise for an early-stage venture Taslan was backing in lab-grown regenerative skin care. The first thing we did, that morning, when everyone had seen to their needs, for stimulants or spinal twists or quiet time watching the day fill in, was watch a film of sea slugs regrowing their bodies from the head, the founder narrating excitedly over the music—oddly jaunty, like some unreleased cut from the Synergetic Voice Orchestra—pointing out how the heart lay on the far side of the breakage plane from the head, as did the digestive system, explaining how, by tying the neck with a loop of nylon thread, you could induce the slug to jettison its body. We watched in time-lapse as the tissue surrounding the nylon loop decomposed, turning cloudy, like spun sugar. At twenty-two hours, he said, jumping up and gesturing at the wall where we’d projected the image, the head separates from the body. We watched the head drag itself off, a tremor in the antenna-like rhinophores.

Takes about a day for the wound to heal, he continued, another week for the heart and parapodia to start coming back. Nine days post-intervention you could see the new heart beating. The image dissolved. We saw a half-slug, just the head and neck, capped off, at the rear, by a small loop of parapodium edged in black. At the anterior end the rhinophores were intact, the orange tips offering a pleasing contrast to the desaturated green of the head, and at first I thought it was using them to get around, but no: it was dragging itself forward by the mouth and ventral surface, same as any other of its kind. The body was covered in the dark flecks, not chlorophyll but some kind of autologous pigmentation, characteristic of its kind. It did not appear to be in distress.

At seventeen days, regeneration was more or less complete. The film ended with a still of an intact specimen of Elysia viridis. Our hero stood in the projector beam, so that the slug’s body was projected partly on his body, partly on the wall, calling our attention to the green speckling that marked the presence of chloroplasts in the tubule cells of the digestive epithelium, distributed, in this species, over the whole of the body, from the tips of the rhinophores to the edges of the parapodia. The slugs were said to be solar-powered, because it seemed, though the evidence was inconsistent, they could subsist, for a time, on energy generated by photosynthesis in plastids extracted from the algae they ate. It’s more prominent, he said, stroking his handlebar mustaches, in the fed state. The image dissolved into a panel of three stills, side by side, E. viridis, E. marginata, E. chlorotica, the lasta vibrant green. We listened, rapt, as he explained what made it so remarkable that the plastids should survive in the cells of the new host, in some species for weeks, much less that they should continue to function. Endosymbiosis, he said, is not like swapping a battery, the chloroplast genome has long since lost many of the genes essential to its own upkeep, including some of those implicated in photosynthesis itself. These are encoded in the nucleus of the endosymbiotic host—the alga—their expression mediated by signals from the plastid. In fact, signaling between plastid and host is bidirectional, the maintenance of plastid structure and its acclimation to changes in photoenvironment a product of ongoing coordination between the two. Selection, he added, operates on the plastid–host ensemble. We nodded thoughtfully.

There had to be a history of horizontal gene transfer between algae and sea slugs—even newly hatched slugs that had never been fed had the genes for maintaining chloroplasts in hospite—and this must have happened a number of times, for every species had evolved to rely on a different alga.

How had it happened? No one knew. It was clearly fitness-enhancing, though the mechanism seemed to vary from one species to another. Fed slugs raised in light produced more offspring, and these tended to be bigger at hatch. No more than what you’d see with two days’ growth post-hatch, but that’s a big advantage—like an eighteen percent enhancement of survival odds.

And it had to be implicated in how the head could survive without circulatory or digestive system—and long enough to grow a new body. The fixed carbon, he said, extending his thin arms in what we took for a gesture of wonderment, had to come from somewhere.

The exciting thing, said Taslan Poplar, was what it meant for skin care. We turned to regard him, standing at the rear, hands braced against the long table that divided the kitchen from the rest of the loft. He wore a shirt of the kind I would come to associate with him, a close-fitting fatigue jacket in an abraded sateen, and two-pocket cargo trousers in a herringbone twill. The rice cooker chirped and we regarded it, perched at the far end of the table. It purred and ticked, a fireworks animation filling its segment LCD. Its ovoid form, the same cream color as my neighbor’s fleece, evoked a visitor from the deep future, when life had evolved to the point that no animal could survive without a shell of tempered ABS, when the fitting of your first shell had become a ritually circumscribed part of the birth process.

Trying something new this season. Many thanks 🙇 — and if you know of anyone who might appreciate STUFF, by all means send it along. —Josh