As a side note, easily the most well-known and common "extremozymes" are the high-temperature DNA-dependent DNA polymerases. These polymerases are purified from deep-sea vent/hot spring bacteria such as Thermus aquaticus and Pyrococcus furiosus, and function perfectly well (and do not quickly degrade) at temperatures over 100 ° C. These are used for the polymerase chain reaction (PCR), as they eliminate the need for fresh polymerase to be added after every 94 ° C denaturing step. This allows automation of the reaction by a thermal cycler, without constant human intervention.