why do monera live in extreme habitats?

Kingdom Monera includes unicellular organisms which do not contain nucleus , i.e, prokaryotic cells. These are unicellular organisms which are found in each and every place on earth. They exist is extreme habitats like high and low temperatures,  high pressure, high salinity, in acidic as well as basic conditions, etc. They can exist in such variety of environments as they are single cellular organisms and are adapted to survive in such extreme situations. They have specific enzymes and structure to survive in extreme habitats.