Always wondered what these are...?

[Overdrive]

I have wondered for quite a long time, every single time I see them, just what these things are under our Boxsters:





I saw a pre-03 S driving down the highway today, and as I came up behind him I could see that the left one of these was just completely gone. I've noticed on my own base model in pictures that one of them appears to be a bit bent, but still intact. Even in the picture above they don't appear to be symmetrical.

So what are they? Do they serve a purpose?