Genesis Prime

Genesis prime is one of the Galaxies greatest mysteries. It is a mysterious planet that seemingly 'jumps' around the Galaxy. In the history of the Imperium it has only been seen a dozen times, and each time in a different part of the Galaxy. While expeditions have landed on the planet there have been no recorded interactions with sentient life forms, and those who remain on the planet inevitably disappear when it does.

Initial Discovery
Genesis Prime was first discovered by the Imperium during the last years of the Great Crusade by the Primarch Sanguinius. Upon entering the system he was amazed to find a world that seemed a perfect paradise, with a amazingly diverse set of ecosystems and life forms, yet had no sentient life that could be discovered, nor any sign of them. Strangest of all was that while in the system, all among the Blood Angels who had any form of psychic potential could feel an enormous warp presence that seemed to move around the planet.

After weeks of searching for the source of the presence unsuccessfully, the Blood Angels were forced to bring the Great Crusade to other worlds and left the planet, leaving only the beginnings of an imperial colony and a tracking beacon. When they returned 2 years later, they found the entire planet missing.