A large, bell-shaped ciliated protist. The cilia at the open end of the bell sweep food into the oral cavity where it is ingested by phagocytosis. The large, circular colorless organelle is the contractile vacuole. This organelle functions to offset in flow of water into the cell by osmosis. The contractile vacuole fills with water which is then expelled as the organelle contracts. You can see the action of the contractile vacuole in the video.
Found in a vernal pool.