X350 rear suspension

[andymadmak]

Last night I ran over a piece of truck tyre at high speed. (didnt see it till last second and could not avoid it)
There was a thump from underneath, but the car drives fine.
I checked this morning and as far as I can see the only damage is to a bar that runs transversely across the width of the car between the front set of rear suspension mounts. It appears to be slightly bent. Is this important? What does this bar do? (it does not look like an anti roll bar)

Andy