Binucleusdetritivorus corymbi split from Mega Binucleusdetritivorus in response to predation. The individual cells remain largely the same, but they no longer form large, easy-to-graze mats. Each cell can live independently, but they will gather together into clusters when they find areas of rich nourishment, like a newly fallen carcass. Such clusters also form much like the ancestral mats, as individual cells split in two. However, the cells in these clusters scatter when disturbed.
When clustered together, these cells retain the ancestral nutrient and energy exchange, as well as their ability to stick together. They no longer form neat mat arrangements, though, being more like haphazard groups of however they happened to stick together. Their ability to move is quite limited, largely inching their way across a two-dimensional surface until coming across another of their kind. Their most effective system of dispersal is to simply stop adhering, allowing them to get swept away and drift on the current.
As the cells move largely two-dimensionally, their clusters are invariably flat, looking like little more than a minuscule stain. However, once a cluster becomes large enough, they will start to slide one atop the other to form a little ball in which they exchange genes and thereby produce offspring sexually.
Scattering and dispersing don't necessarily keep individual cells from being eaten, but it does make it harder for large populations to just get grazed away. Due to these adaptations to deal with grazers, they've spread further into coastal regions where many sorts of binucleid worms are present.