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.
Size and shape. Both archaea and eubacteria are similar in shape and size. They are both found occurring as rods, cocci, spirals, plates, coiled etc. The general cell structure of archaea and bacteria are the same but composition and organization of some structures differ in archaea.