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.

Due to his enormous size, Renzan is often mistaken for a small mountain, especially when he enjoys one of his year-lasting naps and doesn't move an inch. Renzan rarely moves, even when awake, but surprisingly, can be quite the talkative dragon. Too bad one has to be able to communicate telepathically to have a conversation with him, for he surely has much interesting things to tell, after observing his surroundings for so long. Renzan's secret hobby is the human psychology.