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.
Both archaebacteria and eubacteria are single-celled microorganisms, which are usually called prokaryotes. The main difference between archaebacteria and eubacteria is that archaebacteria are usually found in extreme environmental conditions whereas eubacteria are found everywhere on earth.