Thanks again for the comments guys!
I don't really know what exactly caused this, I have had the two linkia starfish in a 40 gal mixed reef for about 8 months...tank has been setup for about 16 months.
Water parameters are pretty normal except my pH usually runs pretty high peaking sometimes at 8.5 in the evening.
I feed Marine Cuisine, Rods Food Original Blend and Reef Nutrition Phyto Feast in cycles to offer varying foods.
I do weekly 20% water changes, and after the water change, I dose iodide, strontium, and amino acids from Seachem.
Check out my tank:
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