Plasmid
Plasmids are transferable genetic elements, or "replicons", capable of independent self copying in a suitable host. Plasmids can be found in all three major domains, Archaea, Bacteria and Eukarya. Similar to viruses, plasmids are not considered a form of "life" as it is currently defined. Unlike viruses, plasmids are "naked" DNA and do not encode genes necessary to encase the genetic material for transfer to a new host.