Plants grass-green to dark green in colour, stiff and brittle, hemispherical or irregularly cup-shaped, hollow, globose, coenocytic, 2-4 cm diameter; generally single layer of cells formed by segregative cell division resembling large, polygonal, honeycomb-like cells, attached to each other by rows of hapteroid cells at segment junction, and attached to the substratum by rhizoids produced from basal vesicles; polygonal cells 2-4 mm broad; tenacular cells 30-50 μm long and 20-40 μm broad.