bseeto wrote:
Lubo,

Your coral is 太陽花. It does not require light, so it usually opens at night.

From your photo, a lot of the polyps are dead already but you may be able to save what is left. Remember to FEED them fish food when they are open. They may be dying of starvation.

By the way, how large is your tank? Remember to change water every week.

With a small tank like this, you are doing a very very good job. It is time to stop buying new fish, sit back, relax and watch your fish grow.