Methanosarcina archaea. Coloured scanning electron micrograph (SEM) of Methanosarcina mazei archaea (round). Archaea are single-celled organisms that are like bacteria, but also have characteristics of other organisms. Clumps of these cells are seen here. M. mazei is anaerobic, and is found in places with little or no oxygen. It is one of the methane-producing organisms that digest decaying organic matter, and are found in lake sediments, rubbish dumps, and also in the intestines of some mammals and insects. They can survive in conditions that would be deadly to most other forms of life, and so M. mazei is also known as an extremophile. Magnification: x23,700 when printed 10cm wide.