Elpis

Elpis was a vault key disguised as the moon of Pandora.

Geography
Elpis is tidally locked, meaning one side will always face Pandora's surface.

History
Elpis was built by the Eridians to act as a key to imprison The Destroyer within Pandora's interior. The Eridians realised that their self sacrifice in the creation of the Great Vault meant that the key could not be disposed of, and thus decided to disguise it as a moon which would not seem conspicuous, even to the inhabitants of the planet below.

Fauna

 * Kraggon
 * Rathyd
 * Shuggurath
 * Thresher
 * Tork