Halobacteria
Methanobacteria
Methanococci
Methanomicrobia
Methanosarcinae
Methanopyri
Archaeoglobi
Thermoplasmata
Thermococci
The Euryarchaeota are a major group of Archaea. They include the methanogens, which produce methane and are often found in intestines, the halobacteria, which survive extreme concentrations of salt, and some extremely thermophilic aerobes and anaerobes. They are separated from the other archaeans based mainly on rRNA sequences.