I have a Kenya Tree Forest and that is what they do sometimes. Mostly when they are getting ready to drop a branch (new coral) other times when it seems to grow. I have had them close for over a week and then open up and all is fine.
With out joking I have had and sold or traded or given away at least 150 kenyas in 3 years. I have so many I moved most of them too my 55 fowlr
and they are doing great under 80watt NO
bulbs.. Great starter coral and does well under all lighting, VHO
if high enough.