Cafeteria cells are encountered as very small sessile or free-swimming naked trophic cells.

Uninucleate trophic cells are approximately bean-shaped and only 3-10 µm long. The two flagella are subapically inserted, often from a conspicuous pocket over which hangs a liplike protrusion. The anterior flagellum is usually directed forward, the posterior flagellum backward. Sessile cells rest on the tip of the posterior flagellum, with the anterior flagellum beating in a helicoidal fashion and directing a current of water onto the cell body. This behavior is diagnostic for bicosoecids. For additional pictures of Cafeteria cells, go to the micro*scope.