So my painfully, wonderfully teal Geo "Stumpy" has his problems... went through the whole engine-drops-dead-for-no-reason thing since I bought it used a while ago, and it's hitting a new record by being out of the garage for over a month!

The slow setting for the windshields doesn't work, the windows get stuck, the right door has a hole somewhere, and so on and so forth, but he works! YAY!
Then today I was driving home when I suddenly heard a terrible metal scraping sound and quickly pulled off into a parking lot. I went on my stomach at the back of the car to take a look and saw a hunk of sheet metal hanging off within arm reach. I couldn't get it off, but bless everything I saw a cop, who yanked if off for me

and I drove it the remaining few blocks home.
So now I have a curved hunk of strong and dirty sheet metal, 11" x 17 1/2", sitting in my front room. What is it and should I be worried about driving to the garage?

~ringo_desu