Bio Shells are a type of artificial lifeform, capable of acting of their own accord and identical to humans in appearance, but capable of being overridden and controlled by anyone with the proper equipment and pass code; usually the Bio Shell's owner, known as its Mind.

Bio Shells, unlike androids, are biomechanical, crafted of artificial tissue and relatively crude recreations of the workings of a human body. However, their artificial brains can be easily altered, reprogrammed, and added onto, unlike a human. Modern Bio Shells have been refined to be able to think in ways never before seen in artificial intelligence, nearly indistinguishable from a real human.

Most Bio Shell control units are in the form of large headgear, which inputs to and receives impulses directly from the brain, effectively causing the Mind to become the Bio Shell when the control unit is in use. All senses of which the Shell is capable are transmitted to the Mind through the control unit, though safety features prevent the Mind from experiencing extreme pain and shock.