Archaea
Archaea are a group of single-celled microorganisms. They were first discovered living in extreme environments, where other organisms could not survive. There are three main types heat lovers, salt lovers, and mathane makers. Heat lovers live in ocean vents and hot springs. Salt lovers live in environments that have high levels of salt such as the Dead Sea and Great Salt Lake. Methane makers give off methane gas and live in swamps and animal intestines.