When I first saw it I immediately thought it looked like a snatch block with the wooden pieces and pully missing. Possibly an older version of a snatchblock?
My first-impression when viewing the photo was that the iron object is a singletree-hook with half of its "sleeve" portion broken off -- and like Creskol I was waiting for the requested additional photos for certainty in identifying it. But no additional photos ever got posted. Oh well... my point is, I agree with DCMatt.