Semi-rebus sign of the Garden of Eden, floating in the dark. A dynamo, set up here to create compass-confusing magnetism. This small magnet-field also protects this place from some little particles that generally aren't allowed into healthy human environments. Earth has a magnet in its belly, and Mars doesn't... that's why we have people who wonder how to get of the planet, and Mars doesn't have anyone at all (they left a while ago, not during my watch).