Unicellular, may form colonies with oval-shaped or oblong cells clustered densely and evenly within firm and abundant mucilage, although the mucous sheaths of individual cells are indistinct. The colonies are often macroscopic, well-defined or irregular in shape, and may be free-floating or sedentary. The cells are gray, olive, or bright blue-green in color, and have granules but lack vacuoles. In colonies, the cells form a single layer often with cells that at least in regions seem to be aligned in rows. Some species reported as solitary motile forms, but edges of genus remain unclear.