Is this part of my car?

[robkay]

I had just finished up rotating the tires on my '07 hatch a couple days ago and when I finished up on the driver's side I found this plastic thing laying on the ground. The weird thing is I didn't see it on the ground when I jacked the car up, only when I was finished and getting ready to clean up which causes me to wonder whether it fell out from somewhere underneath.

It's a black, hard plastic (not rubber) piece about 1-3/4" long. 3 edges have that notching, one edge is smooth. It's sort of a trapezoidal shape, although one corner is a 90. The edges seem to have a very slight concave curve to them. Both "sides" look the same.

Anyone know what the heck that is?