Flagellates look like round revolving spaceships with 'antennae'. Those antennae are what these small algae use to move around and they are called cilia. You could say they are their legs. Despite these 'legs', they don't move all that quickly: a few meters per hour, just enough to keep from sinking. Some species of flagellates have external skeletons (dinoflagellates, coccolithophores and siliceous flagellates) while others have no skeleton at all. Flagellates make up an important group among the phytoplankton.