Monotypic prehistoric sponge genera

Otavia antiqua is an ancient sponge-like multicellular organism found in the Otavi Group (the generic name being the namesake) in the Etosha National Park, Namibia. It is claimed to be the oldest animal fossil, being found in rock aged between 760 and 550 million years ago. The oldest Otavia fossils are from the Tonian period, before the Cryogenian glaciations, but the latest found were from the Nama Group rocks of the Ediacaran period.