a Archean is a single celled microorganism and has no cell nucleus and Bacteria <span>constitute a large </span>domain<span> of </span>prokaryotic microorganisms<span>. Typically a few </span>micrometres<span> in length, bacteria have a </span>number of shapes<span>, ranging from </span>spheres<span> to </span>rods<span> and </span><span>spirals</span>
