Metal stress detector

Metal stress detectors were robotic servants employed by the Daleks aboard their flying saucers. Equipped with a basic artificial intelligence, the metal stress detectors constantly crawled about the floors and walls of the saucer, looking for faults in the metal. If they detected any, the lights on their backs blinked red and they emitted a high-pitched, wining alarm sound. (PROSE: Inside a Skaro Saucer)