The condition in which the entire body of an adult animal or plant consists of a fixed number of cells that is the same in all members of the species. This phenomenon is also called eutely. The largest group of animals exhibiting eutely are the nematode worms, one of the largest of all animal phyla, and of great medical and agricultural importance as parasites of plants, animals, and humans. A plant that exhibits eutely is usually called a coenobium. Many species of semimicroscopic aquatic green algae exist as coenobia, such as the common Volvox and Pandorina.