Random Metal Bracket found in door! Help!

Hey guys, so I was replacing the stock speakers and found this painted metal bracket loose in the driver side door. It was just laying in there behind the speaker. I asked my Toyota dealer and they act like they dont know what it is. We looked over all the parts diagrams and can’t find anything that resembles it.
Do any of you guys recognize this? Im about to chalk it up to something left in the door on accident from the factory, maybe how the hang the door to paint it or something...

Any help would be appreciated! Thanks!

 

That's the rust accumulator module. It's a sacrificial piece of material in the door that rusts so the actual truck doesn't.

 

Just a wild guess but it could be an installation fixture or a jig of some sort they used during assembly of the vehicle

 

Definitely going with FOD.
https://en.m.wikipedia.org/wiki/Foreign_object_damage
At least it wasn't a bucking bar...

 

These comments are making me feel better! Haha