Sun Coral?

[kwirky]

feed 'em with a "one two punch". When the lights go out (or at the dusk part if your lights have a dusk/dawn effect) target feed them once with frozen mysis. About 2 hours later go back and the polyps should be open and sticky and do the "real" feeding again with mysis.

They're non-photosynthetic so you'll have to feed them a good food such as frozen mysis.