Doctor Who: The Hand of Fear (TV)

The TARDIS arrives on contemporary Earth, where Sarah comes into contact with what appears to be a fossilised human hand. This is in fact the last surviving fragment of a Kastrian called Eldrad, who was blown up in space as a punishment for attempting to wipe out his own people. Eldrad's essence lives on in a blue-stoned ring, which the possessed Sarah removes from the hand and places on her own. She then takes the hand to the nearby Nunton nuclear research and development complex where it soaks up the radiation from the reactor core and regenerates into a complete being.