[Mel Diablo]

I have this strange square crack (i don't know how else to describe it) in the front bumper on the right side. It appears to be a perfect square about 1/2 inch by 1/2 inch. As far as I know there has been no physical contact with anything that could cause this. There are no scratches, dents or gouges in the bumper to indicate any kind of contact.
Anyone have any ideas?
I am attaching a picture.