Spherical to ovoid blue-green cells arranged in flat sheets a single cell thick, comprised of squareish clusters of four cells embedded in mucilage. Organelles absent, but granules/vesicles common inside the cells.
Merismopedia, Taieri River, X640. Photo: Otago Regional Council & Manaaki WhenuaMerismopedia, X1000. Photo: Phil Novis, Manaaki Whenua