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.
1 2. 2  ARCHAEBACTERIA â¢ Archaebacteria are the oldest organism living on Earth. 3  They are unicellular prokaryotes-microbes without cell nucleus and any other membrane-bound organelles in their cells-and belong to the kingdom, Archaea. ARCHAEBACTERIA â¢ Archaebacteria are the oldest organism living on Earth. 2  They are unicellular prokaryotes-microbes without cell nucleus and any other membrane-bound organelles in their cells-and belong to the kingdom, Archaea. 3  They were first discovered in 1977 by Carl Woose and George E. Fox and classified as bacteria.