Griffelian

The Griffelians were amorphous masses of protoplasm who lived on Griffelian V. When Sarah Jane Smith asked "Tell me something I don't know" to K9 Mark III, K9 took the phrase literally and began to tell her about the Griffelians. (COMIC: City of Devils)

Behind the scenes
In the Audio Visuals story Subterfuge, Cuthbert was revealed to be a former human who converted himself to a Griffelian and used Griffelian V as a core base of the Conglomerate.