Archeabacteria

The Archeabacteria are a group of single-celled micororganism. A single individual or species from this domain is called an archaeon (sometimes spelled "archeon"). They have no cell nuclus or any other organelles within their cells.

http://en.wikipedia.org/wiki/Archaebacteria

http://trc.ucdavis.edu/biosci10v/bis10v/week7/7webimages/84150f.jpg