The spirochete symbiotic associations shown here are likely to have evolved convergently under anoxic conditions from unassociated free-swimmers normally seen in hindgut preparations and independently of Proterozoic eukaryosis (Margulis et al., 2006).
In the eukaryosis process, motile spirochetes integrated with pleiomorphic sulfidogenic archaebacteria in Proterozoie Eon seas.