Need help identifying this part

Hello all just joined this form. This past weekend I spent a day of boat with no problems until loading back on trailer while giving it some throttle to get onto the trailer I noticed vibration. After removal from the water I seen this hard plastic bushing looking part behind the prop wedged in between prop and the large spanner nut. This boat is new to me so not sure if someone else left this in exhaust somewhere. I did have lower unit off to change impeller a month ago and did not see this then, boat has been out 6 times since impeller change. This is a 5.7 mercruiser with an Alpha One gen 1. Can anyone help me identify were this came from?

Have never seen anything like that used in any outdrive

Thanks Bt Doctur! Could this have came from further up like bellows or Y pipe?

nothing that looks like that, only way it could get down that far would be during a wp repair and fell or was accidently knocked down there