Quick engine question

[Tj-zetec]

Nice simple one for you...

What does this bit do??

I'm talking about the little silver plate that sits more or less over the bottom right hand corner of the valve cover.

Since this photo was taken I've had a complete exhaust installed including extractors so the tin plate covering the shorty and the cat are gone and that little plate was all that was left.

I took it off when i changed the valve cover gasket a few weeks ago and as i was putting it back together i realised it served no apparent purpose.
I thought it looked pretty ugly so i left it off. everything else went back on including the lug that the throttle cable is clipped onto.

I'm just wondering if it does anything incredibly important and if i should have left it on. I still have it... somewhere.