Family: Colonies of a fixed number of cells (4, 8, 16, 32, or more) arranged 2- or 3-dimensionally; cells spherical, ellipsoidal, polygonal, etc. in shape; chloroplasts 1 or several, plate-like in shape, with 1 pyrenoid; asexual reproduction by autocoenobium (Illustrations of The Japanese Fresh-water Algae, 1977).
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).

C. astroideum 2 clips colonies of 32 cells colony 50 μm cells μm Hiroshima, 1998

C. cambricum 2 clips colony 26 μm cells 8 μm Shinrin koen Saitama, 1998