Hyperthermophiles live in extremely hot or acidic water; some species can survive temperatures over 100 degrees Celsius. The famous hot springs in Yellowstone are home to this type of Archaea. They also live around deep-sea vents. Most hyperthermophiles are chemoautotrophs, meaning that they use chemicals found in the water leaving the vents to directly produce ATP. These hyperthermophiles often make the pools a greenish color due to their metabolic waste. They may also feed on dead organisms that have sunk from higher levels of the ocean.