Gonium pectorale; Print; Gonium is a genus of colonial algae; a member of the order Chlamydomonadales. Typical colonies have 4 to 16 cells; all the same size; arranged in a flat plate; with no anterior-posterior differentiation. In a colony of 16 cells; four are in the center; and the other 12 are on the four sides; three each. A description by G.M. Smith (1920; p. 94):