Device on the right side of the muffler

What is your question?

I have a 2012 Rogue SV, which is an excellent car. There is a device on the right side of the muffler and beside the rear wheel on the passenger side. It is shielded by a metal box that is so rusted and the bottom part of the box is almost gone. I tried to google it with no avail. I want to find out the part number for a replacement of the metal shield. Thank you. — Tony

How long has your 2012 Nissan Rogue had this problem?

More than a month