Orange Cup Coral won't open
 

Just recently added an orange cup coral and have been trying to get it to open up to feed. I have tried isolating it in the tank and in a separate container while feeding it mysis. Last night it started to puff up and I could make out a few tentacles emerging, but this morning it was all retracted again. I know that once the tentacles are extended, feeding it will be easy. So I'm looking for ideas as to how to get it to extend the tentacles.

This question is not simple to answer. It could be stressed or your water conditions are not acceptable. You may not have acclimated it long enough. Only time will tell.

Make sure it has the proper flow and is not being bugged by other creatures in tank. Also dont put it in direct flow from a powerhead.

Is it a Fungia? If so that sounds like fairly normal behavior.