My mechanic showed me this last weekend when I stopped by to say hello. C-172 with an O300 motor; non-ferrous part found in the oil screen, spin on filter was clean. I'd say just over an inch wide. Appears failure was at the oil flow holes - at least that's what they appear to be to my untrained eye. Not my engine, just curious what this might be since i have same motor at TBO. I'd consider this pretty serious were this found in my oil screen. At any rate, it's parked in the back of the hangar, where birds that aren't flying anytime soon go.