Glitterspeck

Glitterspeck evolved from rainbowhedrons that settled on the ocean floor in adulthood. They have grown to four millimeters, bigger than any rainbowhedron. Usually, they settle on the sand or silt, partly burying the bottom plate, but their range is full of the fast-growing perfectogon crystalmat, so they'll often rest on that. They'll easily roll with currents, but this is no great problem.

After settling in position, the pores in the bottom plate expand to allow more of the soft core to reach outward, feeling for detritus or latching on to the mycelium of a perfectogon crystalmat and absorbing nutrients from it. The photosynthetic pigments stay mainly in the greener part of the spectrum, due to being in brighter waters, even extending into a slightly bluer green range at the tip, though they become more golden near the base, which is usually shaded. The bottom plate becomes bleached of photosynthetic pigment and appears a pale reddish gray when the glitterspeck is turned over. When this happens, it will grow new pigmentation over the next several days.

Internally, they have repurposed the air- and water-filled chambers that allowed rainbowhedrons to adjust their buoyancy. Most of the interior is filled with soft core tissue, but they have digestive and reproductive pouches near their pores, which can fairly easily convert from one to the other based on whether digestive enzymes are present. These digestive pouches secrete enzymes that exit the pores to digest whatever it's touching, and can suck in and expel water (adapted from their previous use) to aid ingestion and excretion. This includes enzymes to erode perfectogon crystalmat mycelium where it touches the glitterspeck, allowing it to absorb a thin layer. The reproductive pouches produce two types of gametes (one from the shell, one from the core), which they spawn and take in from outside, and they bud off juveniles, whether they've been fertilized or not. These juveniles exit through an enlarged pore that forms for them and are indistinguishable from rainbowhedrons.