the hard, variously colored, calcareous skeleton secreted by certain marine polyps. 2. such skeletons collectively, forming reefs, islands, etc. 3. the solitary or colonial polyp that secretes this calcareous skeleton.
Ancient methanogens are the source of natural gas. Halophiles are bacteria that thrive in high salt concentrations such as those found in salt lakes or pools of sea water. Thermophiles are the heat-loving bacteria found near hydrothermal vents and hot springs.
Methanogens have been found in several extreme environments on Earth-buried under kilometres of ice in Greenland and living in hot, dry desert soil. They can reproduce at temperatures of 15 to 100 degrees Celsius. They are known to be the most common archaebacteria in deep subterranean habitats.