Karnas'koi

The Karnas'koi, also called "lurkers", were vast, winged Great Old Ones. Their language, according to the Seventh Doctor "predates history [and was a] language of the Old Time."

History
The Karnas-koi lived on Earth up to six million years ago, but their society collapsed and four of its mightiest went into a self-induced sleep within their Citadel as it sank beneath the waves. On the ocean floor they had been contained by a "sleeping chant" and their release requires two keys - one is of crystal and opens the surface Citadel, the other is golden and opens the ocean floor and the centre of the universe, finally and fully releasing the Lurkers. (AUDIO: Lurkers at Sunlight's Edge)