Megaluthian slimeskimmer

Megaluthian slimeskimmers were a sentient species. At some point in history they exploded the third planet of an unspecified star system. (AUDIO: Neverland)

Behind the scenes
They were first mentioned in the non-canon Dimensions in Time, in which the Third Doctor stated that he should be taking it easy, not bounding around like some Megaluthian slimeskimmer.