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.
There are three major known groups of Archaebacteria: methanogens, halophiles, and thermophiles. The methanogens are anaerobic bacteria that produce methane. They are found in sewage treatment plants, bogs, and the intestinal tracts of ruminants.
Archaebacteria. The archaebacteria kingdom (Archaebacterium in Latin) is made up of single-celled organisms and the name of the kingdom means âancient bacteria.â Scientists actually believe that members of the archaebacteria kingdom were among the first life forms on Earth billions of years ago.