0 a type of microorganism (= extremely small living thing) similar to bacteria but with a different structure, thought to have existed for billions of years: --
The methanogenic archaea (former archaebacteria) - regarded as strictly anaerobic microbes - are considered as one of the first organisms who settled our planet under extreme conditions.
Extremely halophilic archaea were isolated from ancient salt sediments and were shown to represent novel species.
The vacuum conditions and low temperatures of outer space need not prove lethal, as freeze-drying bacteria and archaea can actually increase their longevity.
In situ metabolism of methanogenic archaea explains the increase in methane at these depths.
Modern archaea-planctomycete microbial associations may perhaps provide a model for early sediment communities.
Early radiation of the archaea at least may be consistent with geological evidence.
The cell envelope structures were one of the first biochemical characteristics of archaea studied in detail.
Despite the unfavourable life conditions, permafrost is colonized by high numbers of viable microorganisms, including methanogenic archaea.
