Mecho-organic vessels were part machine/part living spacecraft made by a race from another galaxy. The vessels existed in a state of symbiosis with their computer and pilot.
The vessels fought in a bloody war until only one, which became known simply as Ship, survived. Ship returned its crew to their homeworld only to find the planet's population wiped out by a plague bomb. Ship's crew all fell victim to the plague except for the pilot, who managed to return to Ship and flee his homeworld and, indeed, his home galaxy. In time, the pilot, Ship, and the computer lost their distinctiveness within their symbiotic bond and became practically a single mind.