I was worried about mine as well since it would not open at all for the first week or so. Then, I tried spot feeding it some oyster eggs/ovary tissue with the flow turned off. There were no tentacles extended at all- I just let the food settle onto the little "cones": Within a few minutes the mouths opened up and they started to draw the food in but still never extended their tentacles. I continued this every day and after three or four days of doing this the tentacles started to emerge in anticipation, but still only a little.: The coral has not fully emerged like I have seen in photos but it getting more and more active in the tank now and it has been nearly a month. It is normally open throughout the day and night. If I add any food to the water it opens right up. It is not shaded and is in decent flow. I suggest spot feeding it and giving it time.