The Robot Guardian of King Nub's tomb, beneath the pyramids of Meroë, was a massive, bronze mechanical monster that was powered electrically. Presumably constructed by Nub himself, the robot was designed to protect the inner sanctum of the tomb — Nub's personal crypt — from intruders. Only by defeating the machine could an intruder be able to escape the crypt.
The Robot Guardian would be activated when a single ruby gem, called "Nub's Eye" (taken from Nub's own coffin), was placed in a socket on the floor. This then opened up a floor panel, raising the monster from out of the floor, revealing the gem to be the creature's "eye." The ten-foot-tall bipedal beast, thus animated, could both attack its opponents with spinning bladed hands or by firing a high-powered, primitive laser beam from its eye. In 1947, an amazed Indiana Jones stumbled across and inadvertently activated the robot while exploring the crypt. After it chased him in the room around Nub's sarcophagus, Jones successfully deactivated it by electrocution, luring it across various electrified floor panels and jumping from its head across to the crypt's only exit.