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.

Petranella Medusa's name means "Little Stone Guardian" in Latin. Petranella, while not being little anymore, is definitely a Stone Guardian. Because she's unable to move very fast, she usually resides near the mouth of the cave. That way she's able to see who belongs in the cave and who doesn't sooner than if she was further back in the cave. If they don't belong she's able to block part of the cave entrance with her heavy stone body, making it harder for them to get in. She loves watching the little hatchlings playing outdoors. She wishes she could see the eggs hatching more often, but it takes her too long to turn around. If she was to turn away from the cave entrance it would put the entire cave at risk, and she just won't do it.