Genus: Colonies spherical, with inner empty space; cells attached to each other by a protrusion of cell wall, arranged in a single layer; cell body mostly spherical with some conical or grobular bulges; chloroplasts cup-shaped with a pyrenoid; reproduction by asexual coenobium (Illustrations of The Japanese Fresh-water Algae, 1977). Species: Colonies of 8, 16, or 32 cells, spherical or ovoid in shape; cells ovoid or cone-shaped, covered with a delicate gelatinous sheath; cells connected to one another by short gelatinous processes; inter cellular space small triangular; cells 6-25 μm diam. (Photomicrographs of the Freshwater Algae, 1996).

31 μm 63 μm 94 μm; x 640

Coelastrum sphaericum, cell body μm long, μm wide, x 640, O-ike (pond), O-ike park, Yabuki town, Fukushima Pref., Japan, August 2003, by Y. Tsukii
31 μm 63 μm 94 μm; x 640

Coelastrum sphericum Nägeli var. sphericum: Colonies of 8, 16, or 32 cells, spherical or ovoid in shape; cells ovoid or cone-shaped, covered with a delicate gelatinous sheath; cells connected to one another by short gelatinous processes; inter cellular space small triangular; cells 6-25 μm diam. (Photomicrographs of the Freshwater Algae, 1996).