Dragons are creatures with nearly unlimited life spans. They can survive for long periods of time, and no one has found a dragon that has died of old age. Adolescence 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. Once they hit adolescence, hatchlings change quickly, maturing to their full forms in only 2 years.

Dragons don't communicate with each other verbally, but they will growl to scare off predators and frighten prey. Young dragons will emit an extremely high-pitched squeal when they are frightened. To communicate, they use telepathy with each other and to speak to other creatures.

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.

Justarius is responsible for all the cave expansion that goes on.  He spends at least part of his days digging tunnels and chewing contentedly on the tasty rocks he unearths.  When the work is done, he often seeks out the young ones, who enjoy climbing on him.  Justarius has a quiet relationship with Sareki, and they seem to enjoy each other's company.  She sometimes joins him in digging tunnels, and he always saves a choice rock or two for her.  He also has an easy friendship with the green Myroku, after previously engaging in a tremendous battle with him over a matter that neither can remember now.