Stone Dragons have a tough outer covering made of a stone-like material. They eat rocks, using the minerals they contain for nourishment and to keep up their stone outer shell. They rarely move, and are the heaviest of all types of dragons. Although they have wings, indicating flight ability, no one has ever seen a stone dragon flying.

Dragons are highly-intelligent reptilian creatures that—from a human perspective, at least—appear to live forever. Many different varieties of dragon exist, each with their own unique qualities, habitats, and behavior. Adolescence in dragons is usually marked by the growth of a hatchling’s wings, although not all breeds of dragons grow wings and some breeds have other traits that indicate the beginning of maturation. In Galsreim, dragons and humans coexist peacefully.

Bearing a name which, according to Viktor, "is heavy just like him" (owner took inspiration from his parents, whose names no-one in the cave can pronounce without choking), Thor is also incredibly stubborn. Viktor and Alex still remember the day  he decided to learn how to swim...and obviously failed.