Stone Dragons are a breed of dragons mentioned once in The Hobbit. Nothing is known about them and they might be an imaginary creature in Middle-earth instead of being a real creature, similar to the Were-worms. Weta Workshop's Cave-Drake might have been based on this dragon. The Elves may also have been referring to a dragon carved out of stone, saying that Bilbo's snores were so loud they could have brought it to life.