Aeriosis
A fictional, subterranean planet that serves as a world of origin for the petralyn species. It was formerly a vibrant planet, having been provided light by a force of pure, concentrated light energy known as the Aether; however, Aeriosis is now rendered uninhabitable, having been stripped of its light and overrun by darkness.
A lot of petralyns had to leave their homes in Aeriosis behind when they evacuated.