what the #$%& is this thing?
 

so im just driving casually, and out of no where, i hear a weird clunk sound.
so of course i pull over to check whats wrong and i find this metal tube thing hanging below my front bumper :confused:
what is this thing? and what does it do exactly?
thanks for the help guys!
http://img339.imageshack.us/img339/2128/photosf.jpg