When first discovered in 1977, archea, these microscopic single-celled organisms were classified as Bacteria. However, later genetic and biochemical analyses showed that they were more closely related to the Eukaryotes. The researchers who discovered this, Woese and his colleagues, proposed the addition of the “domain” as a taxonomic level above that of kingdom, with all life classified within one of three domains, now called Bacteria, Eukaryotes, and Archaea. More than 250 species of Archaea had been described, most fitting into one of two phyla, Euryarchaeota and Crenarchaeota. Many of these live in extreme environments – places where we once believed no life could exist, but there are also the archaea which live in moderate enviroments, mesophilic archaea. Because they have enzymes that can function at high temperatures, considerable effort is being made to exploit the archaea for commercial processes such as providing enzymes to be added to detergents (maintain their activity at high temperatures and pH) and an enzymes to covert corn starch into dextrins. Archaea may also be enlisted to aid in cleaning up contaminated sites, e.g., petroleum spills.