Driftlets
Spreading across the globe, the Driftlets genus is composed of over eighty species. They have avoided competition with their relatives by specializing their body for smaller prey, which has led to some interesting adaptations. As their cells have shrunk, they have also took a wedge shape, and can extend a pseudopod nearly the size of their cell. Their cells have also become translucent to avoid smaller predators. There aren't many differences between each species, aside from their range and size. Species in areas with more food are usually larger, while the opposite can be said for species in places with less food. Some species also live deep in the ocean and are extremophiles, some eating hexatherma, even.
Reproduction
During the summer, when the weather is generally warmer, clumps will periodically reproduce. They do this via as would be expected, one cell splitting into two. They usually exhibit this activity during the day, each cell in the clump splitting into two, leading to massive population booms in a matter of days.