What protist lives as a member of a colony?

One well-known protist that lives as a member of a colony is the slime mold, particularly the species Dictyostelium discoideum. In its vegetative state, it exists as individual amoeba-like cells, but when food is scarce, these cells aggregate to form a multicellular structure that can move together and eventually develop into a fruiting body. This cooperative behavior allows them to share resources and increase their chances of survival. Other examples include certain species of green algae, such as Volvox, which also form spherical colonies composed of numerous individual cells.