Portrait of the planktonic trebouxiophyte alga, Tetrastrum staurogeniaeforme
(Schröder) Lemmermann.The colonies consist of four ellipsoid cells with four to six short spinous projections from the each cell surface. several four-celled colonies may join together to form compound colonie (compound coenobia). Each cell has one plastid and one pyrenoid.Collected from a freshwater pond near Boise,Idaho. July 2005.DIC.