Plate Fell off bottom of J30 - what is it?

[macsnyc]

Hi - I"m a car novice but have a '93 J30. The other day I was driving and suddenly heard this scraping from underneath my car. I stopped and looked underneath and some sort of (rusty) plate was holding on by one screw. As I tried to get home it fell off on a very busy street so I didn't go back to get it. The location of the plate was behind the front wheels, center. I guess it is to protect pipes / part of engine? I'd like to see if I could order the part to avoid high fees at the mechanic.

Thanks!

[driverdriver]

That is the heat shield. If you don't park on grass, you have nothing to worry about.