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.
Archaebacteria Groups. Under the kingdom Archaea, archebacteria are classified into the following phyla: Methanogens harvest energy by converting H2 and CO2 into methane gas. They are found in the intestinal tracts of humans and some animals such as cows, and in marshes.