What is this part and where does it go? I need to know because it was in my trunk when I bought the car and it looks important.

 

It is part of the heater/Ac duct that goes under the carpet and seat for back seat heating/cooling. Can't tell for sure if it's passenger or driver side. It starts at the front side of console, then runs down and back. Not a critical part to have in place. On second look, it is the passenger side.