ARCHAEA
Archaea are a domain of single-celled microorganisms. They have no cell nucleus or any other organelles inside their cells.
there are five major phyla of Archaea:
Archaea
Introduction to the Archaea
What are archaea?
5.6 Archaea
Types of Archaea
Archaea: 27 Characteristics Of These Most Ancient Organisms
Archaea and Their Potential Role in Human Disease