Archea - microorganisms which are similar to bacteria in size and simplicity of structure but radically different in molecular organization. They are now believed to constitute an ancient group which is intermediate between the bacteria and eukaryotes.
Monera is a kingdom in biology that comprises prokaryotes, which are single-celled organism that have no true nucleus. Monera is the most ancient group of organisms on earth, as well as the most numerous. ... Since monerans are prokaryotes, such as bacteria, they have no membrane-bound organelles.