Trachyphyllia with a gaping mouth. Probably not a good thing. Unless it just ate a snail, or something big and hard that is keeping the mouth "propped" open. Hard to tell from the pics, but is there a lump under the greenish skin near the mouth? Kinda looks like there might be in the actinic light picture. If so, I'd say a snail fell onto it, and it ate it. If that's the case, it'll eventually spit it out.
Kind of like this:
<a href="http://s237.photobucket.com/user/K_Nelson_photos/media/DSC05483-1.jpg.html" target="_blank"><img src="http://i237.photobucket.com/albums/ff156/K_Nelson_photos/DSC05483-1.jpg" border="0" alt=" photo DSC05483-1.jpg"/></a>