Protoviramoeba bichroma
Protoviramoeba bichroma split from its ancestor by developing a more specialized life cycle as it spread into regions inhabited by adorbalgae. As before, it is incapable of fully replicating on its own and must enter a host cell, replicate multiple times inside it, steal its organelles, then burst out from its host.
P. bichroma acquires organelles from two different hosts. They gain bioluminescence from rainbowtesta or cupotesta, whichever is present in their range. From adorbalgae, they take photosynthetic organelles as well as the ability to grow light-sensitive eyespots (though these are much smaller in the tiny P. bichroma cells). A cell that was born in a rainbowtesta or cupotesta belongs to the zooplankton stage of their life cycle. One that was born from adorbalgae or that entered an adorbalgae cell later in life belongs to the phytoplankton stage. As phytoplankton, they subsist on photosynthesis, while as zooplankton, they must scavenge for detritus. Some P. bichroma cells have both sets of organelles, which happens if they were born from a host of one type but have entered a host of the other type later in their life. These are the most successful cells.
P. bichroma with luciferin can glow a bright purple. If they also have eyespots, they glow only when they sense other bright lights, but those without eyespots glow at random. Phytoplankton P. bichroma are attracted to bright light, which helps them keep in sunlight but also attracts them to rainbowtesta, cupotesta, and bioluminescent members of their own species. This allows them to signal to each other, resulting in emergent behavior without significant intelligence. They end up flocking around potential bioluminescent hosts and also signaling each other when such hosts are present, and they also congregate in large, dense clouds. In these clouds, the cells are also able to transfer genetic material between one another, though they still rely on their hosts for organelles.
P. bichroma clouds tend to end up a diffuse green due to the phytoplankton cloud, but with bright flashes of purple that ripple through the cloud as neighboring cells signal to each other.