Hela was a frozen world with no atmosphere which first orbited the gas giant Haldora, and later the shadows' mechanism that imitated Haldora down to its gravitational field. Back before the destruction of its parent planet Hela was a colony world of the scuttlers. However, after beginning the process to bring the shadows from their universe to that occupied by the scuttlers, in an attempt to prevent their extinction at the hands of the Inhibitors, the Nestbuilders intervened and destroyed them.
Many years later, humanity colonized Hela. Led by Quaiche, a man who believed that Haldora's failing concealment mechanism was a message from God, Hela became the center of scuttler research -- or rather, the pawning off of their artifacts to Ultra traders.