Answer:
microorganisms that are similar to bacteria in size and simplicity of structure but radically different in molecular organization. They are now believed to constitute an ancient intermediate group between the bacteria and eukaryotes.
Step-by-step explanation:
The Archaea (or Archea) are a group of single-celled organisms. The name comes from Greek αρχαία, "old ones". They are a major division of living organisms. Archaea are tiny, simple organisms.