Wow, that piece looks "rolled, folded and hammered"!
Is it possible for something to drop in from the top, get beat around by a valve and then spit back up into the intake? Years ago, I saw an air filter wingnut get dropped into the running engine through the carb. Lots of clacking sounds before we got it shut off. We found the beat up wing nut in the exhaust manifold so it had made the whole journey through the valves.