midichlorian

• "midi-chlorians are microscopic life-forms that reside within the cells of all living things and communicate with the force. they are symbionts; life-forms living together for mutual advantage. without the midi-chlorians, life could not exist, and we would have no knowledge of the force. our midi-chlorians continually speak to us" (qui-gon jin)
  
  http://www.theforce.net/midichlorians/