Clingowhexia
Clingowhexia diverged when it evolved the ability to develop its flagella into holdfasts. This allowed it to cling to hard surfaces, much like its extinct relative Krakowhydra ancora. Unlike them, however, clingowhexia focused primarily on photosynthesis for sustenance.
Clingowhexia begin life as free-swimming cells, essentially identical to their ancestor. Purple photosynthetic material fills each cell (thicker near the center). These cells have an arrangement of six stiff equidistant "arms." At the end of each arm is a symbiotic cell, now an organelle, with a series of flagella used for locomotion and to ensnare food. Indeed, as juveniles, clingowhexia are even more mobile than their ancestors, as it is this mobility that has allowed them to spread from coast to coast. While swimming freely, juveniles who encounter each other may exchange genetic material but will not themselves reproduce.
Eventually (the amount of time varies from individual to individual), they will settle on a solid surface, one exposed to plenty of sunlight. This is often a rock or grain of sand but could be anything, even a living being. Crystal groves are especially common for this purpose, as their hard and sturdy trunks provide an ideal surface. (Tentacle crystals, on the other hand, are particularly uncommon hosts, as they tend to eat the clingowhexia.)
Once it's found its home, the clingowhexia will convert some of its flagella into sticky clingy holdfasts. This will almost always be the ones at the ends of three arms on one side, forming a tripod shape for maximal stability, but occasionally, if they settle on something with an odd shape, it'll be a different number.
Once there, they take up a mostly photosynthetic lifestyle but will consume organic matter that comes near the remaining flagella. Now they will set to work to reproduce. They use binary fission to spread out across their surface. Each cell remains an independent organism, but in great quantities, they may form a purplish patch. They also bud off smaller cells: juveniles, which freely swim away. If disturbed, adults can also revert to a juvenile state.
Clingowhexia are a ring species. Juveniles in each population can exchange genetic material with neighboring populations: the eastern Glicker coast across the LadyM Ocean to the west of Wright, then along the passageway between Dixon and Fermi, then east of Orpington, and across the Vailnoff Ocean to western Glicker. However, if one were to bring together clingowhexia from the east and west sides of Glicker, the divergence would be too great, and they would be incompatible with one another.
Though stiff, these are fairly soft cells, lacking cell walls. Their best defense against predation is sheer numbers. They also lack resistance to desiccation and therefore will not settle in the tidal zone.