Star Polyp/Starburst Won't Open

[NicoC16]

I have been having this star polyp coral in my tank for six months now and it has been opening every day since I purchased it. All of the sudden it closed itself up for a few days and will not open. I haven't changed anything I've been doing, so I wanted to see what others have to say about this type of coral not opening. I recently bought a sea hare although it shouldn't have caused the issue. Maybe the past water change stressed it out. All of my other corals (lps, soft corals, etc.) are fine. If anyone has any suggestions on why it is not opening, I'd greatly appreciate them. I am very concerned for my coral because it has been three days closed now.

 

[Sniperhank]

How is your alk levels? Have you taken them out to inspect them in case of a nudibranch?

 

[NicoC16]

Are sea hares known for picking at star polyp?

 

[54seaweed]

try taking a turkey baster and blow out all the crud built up on coral
i find mine close up if crud builds up on the coral