Circle of Transcendence

The Red Carnivorous Maw was presumably as its name suggests, a red-skinned carnivore.

In the Tenth Doctor's timeline, some time after the Bowie Base One incident and before he travelled to the Ood Sphere, he saved a planet from the Red Carnivorous Maw. The Doctor later mentioned this adventure to Ood Sigma. (DW: The End of Time)