Mystery Nut?

[kindred7]

Hey all, so here's the story I opened my hatch and found this nut loose in the back. Right behind the rear seats, just sitting there.

Any idea where it's from? It looks like it should be on the body of the car (car paint color is on the nut) but it doesn't look familiar to me. Thanks!

 

[jelloslug]

It's called a PEM nut. It's a self clenching fastener that is pressed into sheet metal. It should not be just rolling around in the car.