Speaking in a deep, echoing voice, the aliens identify themselves as the Mysterons and state that they have discovered the secret of "reversing matter" (a power later referred to as "retrometabolism"). They have the ability to heal any physical injury, and re-create the exact likeness of any object or person – a power they can exercise only after the original object has been destroyed or the original person killed. Dedicating themselves to a "slow, but nonetheless effective" retaliation for the unprovoked attack on their Martian complex, the Mysterons seize telepathic control of Black and return him to Earth, making him instrumental in avenging the Mysterons by acting as their agent and destroying other people and objects, so that they may be re-created under Mysteron control.