Cybermats

Like gross little spies for the Cybermen, Cybermats are insect/rodent-like cybernetic beings dispatched to infiltrate, gather intel, steal electricity and bite humanoid ankles. In New Who episodes like ‘Closing Time’ they were shown to contain organic components.
Podcast C079 Revenge of the Cybermen > > > > > >

An imbecile, a Glitter Gun, and not the Seal of Rassilon
Podcast N086 Closing Time > > > > >

Subterranean Cybermen on a Shopping Spree and A Stormageddon in a Teacup
Podcast C043 The Wheel in Space > > > > > >

The most convoluted Cyberman plot to date VS. The least professional space station crew ever
Podcast C037 The Tomb of The Cybermen > > > > >

Racist Space-archeologists unearth a fortune in Cyber-stencils in this legendary serial.