An orb shadow was a vision that affected people who had had experiences with the orbs of the Prophets. They could occur a very long time after the orb experience, and were said to happen when that person was going against the will of the Prophets, to set them back on the path. Medically, they could be described as hallucinations caused by an excess of neuropeptides in the person's system. Benjamin Sisko experienced an orb shadow in 2372, some three years after his first orb experience. Former Kai Opaka appeared in this vision. (DS9: "Accession")