Insectoid robot (The Sour Note)

A giant insectoid robot was encountered on an Earth-like planet by the Second Doctor and Polly Wright. The Doctor speculated that the robot was being controlled from beneath the surface to guard an entrance to an underground settlement and tested his theory by throwing a rock at it, which it swallowed. Concerned that the robot might have also swallowed Ben Jackson, and observing that it was being controlled by musical notes, the Doctor used his recorder to lure it to the TARDIS so he could examine it with his instruments. When they arrived, the robot attacked them, but they escaped into the TARDIS. (PROSE: The Sour Note ^[+]Loading...["The Sour Note (short story)"])