Charle Frahma in Ulara explains that any power of sufficient magnitude could destroy the Signets, which is how the Divine Dragon was able to destroy one in Deningrad. The Moon Objects were merely a tool, containing an amount of magic power so massive it could not controlled by humans. The body of the 108th species and its housing are so massive that they are held in geosynchronous orbit over the planet and can be seen in the sky of Endiness as the Moon That Never Sets.