The colony shows division of labor. Each sphere is composed of up to a thousand cells, each a biflagellate similar to Chlamydomonas. Asexual colonies consist of somatic or vegetative cells, which do not reproduce, and gonidia, which reproduce, the reproduction being a process of longitudinal division. Sexual or oogamous colonies also contain ova (non-motile female cells) or spermatozoa (small, motile male cells) or both. These cells, near the back of the colony, develop into new colonies, initially with the flagella directed inwards and held within the parent. Eventually the parent bursts and the daughter colonies invert.