Ciliates are well-known protozoa, characterized by a peach fuzz lining of hair-like cilia that let them swim for it, whatever it may be. Ciliates swim wherever water is found: in soils, ponds, lakes, rivers, and oceans.
Other protozoa are not so ambitious. Once settled, sporozoans don’t move. Instead, they lodge inside hosts as parasites.
Cilia are for more than just swimming about. A ciliate sweeps food into its mouth using its cilia. Food is packed into a vacuole which travels the digestive tract, where the contents are broken down via lysosomes until small enough to diffuse through the food vacuole into the cell. Anything left in the vacuole when it reaches the cytoproct (anus) is discharged via exocytosis: directing a secretory vesicle into extracellular space.