Undercarriage Rust Issue
 

Hello all,

I have owned my 2013 autobiography for about 5 years, knowing Ive had some rust issues with my undercarriage. Recently I have had a large panel of the rust break off and begin hanging off of the bottom (I know very exciting). I cannot find a parts diagram that tells me what this part is, hoping someone can help me out. Trying to figure out how serious this is