Cybermat

The Cybermen used small cybernetic creatures called 'cybermats as advanc guards and as attack carriers of plagues.

Cybermats resemble oversized metallic silverfish and have segmented bodies with hair-like tactile sensor probes along the base of their heads. At least three models of cybermat are known to exist, the first with crystalline eyes and antennae through which they receive commands. (DW: The Tomb of the Cybermen)

The second have photoreceptors for eyes instead of crystals. (DW: The Wheel in Space)

The three have segmented, eyeless, flat bodies. (DW: Revenge of the Cybermen)