Rear Bumper removal

Does anyone know what the six pieces of rectangular padding on the inside of the rear bumper cover is for and what its made of?

I removed the bumper cover to install a tow hitch and see that it all seems to be coming off the inside of the bumper and I'm wondering if it's worth the trouble of replacing it.

Are you talking about the white, cottony stuff? I suspect it's noise reduction. I had one coming off and I just used a spray adhesive to put it back up.

You can see one of them in the far right hand side of this photo: