In taxonomy, the Crenarchaeota (Greek for "spring old quality") (also known as Crenarchaea or eocytes) are a phylum of the Archaea. Initially, the Crenarchaeota were thought to be extremophiles (for example, thermophilic and psychrophilic organisms) but recent studies have identified them as the most abundant archaea in the marine environment. Originally, they were separated from the other archaea based on rRNA sequences; since then physiological features, such as lack of histones have supporte… (More on Crenarchaeota)