AHH! Bubble coral!

[fortheloveofcrabs]

Hello,

I've had a bubble coral for about 6 months now, and it has been doing fine, up until about a month ago. It started spending most of its time 'deflated' and not the tissue is receeding. What's going on?! Nothings changed in the tank (IE no new tank mates). Are the sensitive to something? Is there something special to these corals? I was told they are simple. I have a RBA in my tank that's thriving, and other LPS corals that are fine (mostly candy). I also have 2 clows, a damsel and a skunk shrimp.

Please help!

-Pauli