From Creatures Wiki
Aquamite (Aquatophagoides albia)filter-feeding, sea-dwelling insect. In Creatures 3, it drifts through the water in large clusters. It is the lowliest member of the food chain, even lower than the tiny Wyst, and as such they are not always in plentiful supply. In the Marine Terrarium, however, there is an Aquamite Maker gadget that can be used to make more - even on regular intervals, if desired.