This part just fell off my car, what is it? Do I need to get a new one?

[germantorresf]

http://i35.tinypic.com/2rpd539.jpg

is a Nissan Altima 2001
thanks!

 

[guitarpro94]

catalytic converter and yes you need a new one

 

[pbleek]

looks like a heat shield from a catalytic converter, has bolts, should bolt back in.