Hyperthermophiles are extremophile organisms that live best in very hot environments– from 60°C (140°F) up to 100°C (212°F). The best temperature for hyperthermophiles to grow at is around 80°C (176°F). Hyperthermophiles are mostly in the Archaea domain, but some bacteria are able to tolerate temperatures of around 100°C (212°F) as well. Many hyperthermophiles are also able to tolerate other environmental extremes, like high acidity or radiation levels.