I never noticed it for some reason.

apart from the fact that it is several inches across. I missed it the first time too.
Also, if you add a CD or other drive to the front panel, you don't get the drives out thru the inside of the case. Pop of the plastic drive cover bezel on the front and undo three (?) screws. I was set to take the machine apart in all sorts of horrible ways to add a drive to my dad's Yikes mac.