Colonies plate-shaped, more or less square with rounded corners, consisting of 8, 16 or 32 cells in 1 layer; cells usually connected by extracellular matrix comprising three zones (a fibrillar sheath, a tripartite boundary surrounding individual cells, and a fragile gelatinous capsule zone surrounding entire colony); tripartite boundaries of adjoining cells attached or fused with one another; cells more or less spherical to slightly ovoid or pyriform; 2 equal flagella; chloroplast cup-shaped, with anterior eyespot and 1-2 (rarely up to 8) pyrenoids; contractile vacuoles 2, anterior; asexual reproduction by formation of daughter colony by each cell; sexual reproduction isogamous or anisogamous, heterothallic or homothallic; gametes with tubular cytoplasmic protrusions µmating papillae) near base of flagella µmating papillae lacking in Gonium multicoccum); thick-walled zygotes produced after gamete fusion; on germination 4 separate or joined gone cells arise, each producing a 8-, 16- or 32-celled vegetative colony; palmellae and akinetes known; nutrition phototrophic or chemo- or photo-organotrophic; freshwater, frequently in temporary or permanent pools and ponds.