I think its actually the exhaust chamber that took the biggest hit. The actual exhaust (you can clearly see its the one leading up to the ramp) seems more or less fine.
EDIT: looked a page back and people do seem to wonder what the piece is.
http://scarbsf1.com/blog1/2011/11/24/an ... -exhausts/
(look for the ferrari exhaust chamber; same principle)
http://www.formula1.com/news/technical/ ... /1018.html
(the left red arrow are actually pointing wrong, pointing at the exhaust instead)
Crucially that bit malfunctioning (as in not doing what is designed to do, but for the rest not hurting the car) isn't that a danger for the car; it'll only mean a bit of downforce loss when off throttle, though of course as hot gasses are actually accumulated in it (I dare say that means the temperature is actually higher then at the exhaust exit), its structure still needs to be able to cope with the heat.