Chthonians are described as immense squids, with elongated worm-like bodies coated with slime. Despite their squid-like appearance, chthonians are land-dwellers and are even harmed by water.
Chthonians are powerful burrowers, live for more than a thousand years, and are protective of their young. It is said that a chanting sound accompanies every chthonian, and that by such they can be detected while underground and unseen.
The most important individual chthonian is the gigantic Shudde M'ell, which is worshiped by the rest.