Weirdest Bookmark?

I've seen a lot of odd thing shoved inside books during my years working at an independent bookstore and various libraries, but this stove piece found inside a book returned to my current elementary school library is perhaps the weirdest to date:

It isn't even flat!  Also, this is an elementary school library so it was returned by a kid.  Kids should not be hanging around stoves, pulling pieces off!  This is very concerning...