does it look like that flat square one?
http://z.hubpages.com/u/492508_f520.jpg

any screws on yours?

if not it must just be snapped on..

how brave are you LOL - what I would try is this -
if you can gently slip a flat screwdriver or dull knife along the edge and just try to see if it budges or opens any gap??
very easy so it doesn't crack or break..

I'll keep looking for more pictures/info