Cybermats

The Cybermats are a creation of the Cybermen. Cybermats are small, rodent like robots with antenna for receiving instructions on their heads. Some variants of Cybermats had crystalline eyes or photoreceptors, depending on when they were found (in The Tomb of the Cybermen (Classic series) they had crystalline eyes but in The Wheel in Space (Classic series) they had photoreceptors). Some Cybermats were small enough to fit into a human hand. The look of a Cybermat is similar to a silverfish, with segmented bodies and cilia-like tactile sensor probes along the base of their heads.

A Cybermat from the Classic series

In Revenge of the Cybermen (Classic series), Cybermats had eyeless, segmented worm-like bodies without cilia. Like the Cybermen, the Cybermats were vulnerable to gold, though they could also be disabled using an electric charge. The Cybermats seen in Revenge of the Cybermen could also inject poison into a victim. The Cybermats originated on Mondas early in Cyberman history before most of the planet had converted to be Cybermen. The tombs on Telos also had tunnels designed especially for Cybermats to move around the tombs to the main control room easily.

A Cybermat from the Classic series