The inner sheath of mucilage surrounds either one cell or a recently divided pair of cells in Gloeocapsa. Gloeocapsa is a blue-green algae that is found in wet rocks or moist soils and can be symbiotic with fungi, forming lichens.
Cells of Gloeocapsa may be oval-shaped or ellipsoidal and hemispherical after cell division. They are usually bright blue-green or olive green. The sheath color may be violet, blue, orange, red, brown, yellow or colorless, and it may be affected by pH changes. Some sheaths are more visible than others. When sheaths are not as prominent, the cyanobacteria is placed into a category known as Gloeocapsopsis.