JccEldreth, your "old not sure what it is" mystery object is part of an antique door lock. The square hole in it was for the square iron shaft of the doorknob to fit into. Turning the doorknob turned the square shaft which turned your mystery-object, whose "eccentric rim" retracted the wedge-shaped door latch which fit into the matching opening in doorframe. You'll see your mystery object in the photo below. That photo was used to ID another doorlock part... the blue arrow has nothing to do with your find.