Serpent Star Growing???

[Erickrebs76]

I have a pretty small serpent star (hitch hiker on live rock) I was feeding this morning and saw his central disc was enlarged like an upside down cone. Is he growing or is something wrong? All others doing great. Its a 24 gal nano cube with an orbit led light and T5 10k and actinic supplement no Lid. I can't find any info. Any info please. Eric
Sal 1.026
Nitrate 5-10
ph 7.8-8
DKH is 21-23

 

[BranchingHammer]

Pretty sure that happens when they eat a chunk of food