 "Ignicocci" live in a temperature range of 70–98 °C (optimum around 90 °C).They gain energy by reduction of elemental sulfur to hydrogen sulfide using molecular hydrogen as the electron donor (Huber et al., 2002).A unique symbiosis with (or parasitism by) "Nanoarchaeum equitans" has also been reported (Huber et al., 2002).