Strain 121 (Geogemma barossii) is a single-celled microbe of the domain Archaea. First discovered 200 miles (320 km) off Puget Sound near a hydrothermal vent, it is a hyperthermophile, able to reproduce at 121 °C (250 °F), hence its name. It was (at the time of its discovery) the only known form of life that could tolerate such high temperatures. 130 °C (266 °F) is biostatic for Strain 121, meaning that although growth is halted, the archaeum remains viable, and can resume reproducing once it has been transferred to a cooler medium. Strain 121 metabolizes by reducing iron oxide.