Nagging question

[Offalmangler]

I have to ask, is it normal for a coral to be healthy one day then the next it be retracted and dark colored? But it still fluffs up hours and hours later?

My frogspawn has had excellent growth. Tank parameters are fine, but recently it has been retracting then fluffing back up later on.

Here is a pic

Here is another one same level in tank. Same flow. Just in the rocks

Should it be placed on the substrate?

 

[spudmclellan]

I wouldn't put it on the substrate as it should be good if its opening up. Is there aything near by that could be bugging it, or is it retracting at night?