Woprat

Woprats were a long-extinct species from Gallifrey. The Second Doctor was surprised to find one in a Type-one TARDIS and wished to investigate. Before he could, Victoria screamed and scared it off. (PROSE: Heart of TARDIS)

Woprats were built like small dogs and appeared like rats, except they had fifteen long, multi-jointed limbs arranged like a spider. Older ones had thin, grey hair. (PROSE: Heart of TARDIS)