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.

The rocky spire that houses the Breedery is gigantic enough that even a stone dragon is tiny beside it, but on the rare occasions that Sedimentarius leaves his accustomed spot, the mountain seems somehow diminished by his absence. Visitors often mistake his somnolent bulk for part of the mountain—a hill, say, or a rocky outcropping. Most of the time, the old stone dragon is content to sleep in the warm sun. Being fed by Lurhstaap, the only reason Sedimentarius has to move is to visit his mate, Shatterstones. Now and then, Sedimentarius will arise and enter the Breedery, following the cavern tunnels deep into the ground. The two will mate, spend a few years together, then separate, with Sedi making the long trip back to the surface alone. Their bond is very old, yet they prefer not to spend too much time together. Both are loners at heart. Still, they have several children together and are known as mates by the rest of the Breedery's dragons.