Plungboll

Plungbolls were tiny, fur-covered organisms approximately the size of Sarah Jane Smith's thumbnail. They were native to the snowy mountains of Gallifrey.

Plungbolls attached themselves to any source of warmth that happened by. Some travellers suffocated to death, covered with thousands of the creatures. To avoid this fate, a chemical called anti-plungboll spray was developed; this substance caused them to drop off their would-be victims, squeaking. (AUDIO: The Ghosts of N-Space)

Behind the scenes
Plungbolls were mentioned in Doctor Who Insider #3.