Monotypic genera

Parakaryon myojinensis, also known as the Myojin parakaryote, is a highly unusual species of single-celled organism known only from a single specimen, described in 2012. It has features of both prokaryotes and eukaryotes but is apparently distinct from either group, making it unique among organisms discovered thus far. It is the sole species in the genus Parakaryon. It is part of the domain Parakarya.

species of bacterium

Obamus is an extinct enigmatic organism from the late Ediacaran of Australia, . It is torus in shape, and is a monotypic genus, containing only Obamus coronatus.

Wutubus annularis is a large tubular fossil from the Late Ediacaran of China and USA, between 551 - 541 Ma. It is the only species in the genus Wutubus.