Some produce thick-walled spores. Those colonizing soils may have been the first tier on the landscape. Some small tubes may exhibit vesicle-like swellings. Thick walls of large tubes contain anastomosing filamentous components.
Thin walls consist of a septum with a complex pore.
Algae consisting of single spherical body 1.5-5 mm diameter composed of an inner and outer zone. The inner zone consists of multicellular filaments oriented randomly, but in the outer zone are radially oriented. A dorsiventral thallus, circular to ovoid up to 5 cm, with clustered spores. The thallus is cellular, upper and lower epidermis with parenchyma, and attached by a ventral holdfast. Spores appear cuticularized, 28-34 m in diameter, interpreted to be in a sporangium at the surface.