These ancient biomechanical constructs were created long ago through the artifice of the Cults Cybernetica and Biologus. Over the millennia, sheen bird numbers have gradually dwindled, their flesh diseased and plumage scarce. The remaining sheen birds are foul things, infested with parasites and filthy with pollution. Occasionally, sheen birds will make their way into the lower levels of the underhive. Here they’re greeted with awe by the devoted of House Cawdor, who view them as avatars of the Emperor’s grace. For high ranking Cawdor gangers, to possess a sheen bird is akin to possessing the direct blessing of the Emperor himself.