Rear swaybar end broke off. Not sure how easy these are to get out...find one at a recycler? IMO...you could drive it...just don't do a lot of hard cornering....fix as soon as possible.It is a 2003, really great car has almost 300,000 miles on it.
MISTAKE!!! I have the same car and got under it to take a look....what you picture is NOT the end of a swaybar...it's a heavy rod that positions the rear wheel front to back...NOT a good idea to drive it. Would not be expensive to fix...but NOT SAFE to drive it.