Frontonia sp. ciliate protozoan, light micrograph. A ciliate protozoan is a single-celled micro-organism. It uses cilia for propulsion and to waft food particles such as bacteria into its mouth. Frontonia are also capable of ingesting larger prey such as diatoms and filamentous algae. Digestion takes place inside the cell within food vacuoles. Microscopic contrast technique: darkfield contrast. Magnification x60 at 35 mm.