Prokaryotes that do not incorporate muramic acid into their cell walls. A highly diverse group of methanogenic (producing methane), thermophilic, acidophilic, and hallophilic (living in high salt concentrations) bacteria that is presumed to represent one of the three primary lines of descent in the living world.

a taxon of primitive bacteria including methane producing forms, red halophilic forms, and others that favor harsh acidic environments. These may be closely related to eukaryotes.

ancient bacteria that have a different ribosomal structure, membrane composition, and cell wall composition than modern bacteria.

archaea

Organisms constituting one of the three biological kingdoms.

The organisms that make up one of the biological kingdoms.