Appearing as nothing more than a vast mass of sentient magma, C'thalpa currently resides in the Earth's mantle, although whether she has been imprisoned there by the Elder Gods like so many of the other Outer Gods, or she simply lies dormant, is unknown.
C'thalpa is the mother to six monstrous children, one of whom is the Great Old One Shterot. The identities of the remaining five have yet to be revealed. She is worshiped by a race of mole-like subterranean humanoids known as Talpeurs, who carry out her bidding in the world above the Earth's core.
- C'thalpa made her only appearance in the collection of French short stories on the Cthulhu Mythos, Paris, Rêve ou Réalité (1988).