Archaea is unicellular and prokaryotic, members of the domain Archaea live in some of the most extreme environments you can imagine. Like volcanoes, hot springs,brine pools, and black organic mud. Indeed, many of these bacteria can only survive in the absence of oxygen. Their cell wall lack peptidoglycan, and their call membranes contain unusual lipids that are not found in any other organism. The domain Archaea corresponds to the kingdom Archaebacteria.