Dragons that, like butterflies, have two stages to their lives. They hatch from eggs into sea serpents. They roam the seas, growing to a vast size. And when the time is right, when enough years have passed that they have attained dragon size, they migrate back to the home of their ancestors. The adult dragons would welcome them and escort them up the rivers. There, they spin their cocoons of sand - sand that is ground memory-stone - and their own saliva. In times past, adult dragons helped them spin those cases. And with the saliva of the adult dragons went their memories, to aid in the formation of the young dragons. For a full winter, they slumbered and changed, as the grown dragons watched over them to protect them from predators. In the hot sunlight of summer, they hatched, absorbing much of their cocoon casing as they did so. Absorbing, too, the memories stored in it. Young dragons emerged, full-formed and strong, ready to fend for themselves, to eat and hunt and fight for mates. And eventually to lay eggs on a distant island. The island of the Others. Eggs that would hatch into serpents.