yellow colony polyp not opening all the way up

[Jhead85]

Any idea why these are doing this...everything else in the tank is doing great but these have never opened up fully and I can't figure it out..instead they just open up just enough to where the tentacles stick straight up..water param are great and the light is a kessil..torch coral..frog spawn other zoas ect all are perfect..any ideas...

 

Also I've noticed in the months I've had them...they were on a snail shell that I glued to my rock and they have started to go lower and lowr and now only 1 is just barley left on the shell the rest have made it to the rock..maybe light is to bright for them?

[Jhead85]

Edited November 6, 2014 by Origami
embedded image for the OP