Took my starter off and this fell. Could someone please tell me what it is

 

It looks like a positioning keeper for parts during assembly. Don't know for sure, but they usually use cheap plastic like that for that application. May have fallen on top of the starter and no one bothered to retrieve it. Maybe someone working in an assembly plant can help.

 

Guess it is a mystery piece, just hope it doesn't belong on my truck

 

^This made me laugh out loud!

 

Put it in the glove box. You may need it down the road. Who knows.

 

Back in the 70's a friend of mine found a coke bottle hanging from a string inside his Camaro door panel. That was malicious. Anything I've heard found in recent years has been extra fasteners and shipping parts which is what that item might be.