Pencil Sea Urchin problems

[flapjak68]

My 2 sea urchins were doing real well for about the last 6 months but now one looks like it's dying and the other is not nearly as active as it was just a couple weeks ago. Nothing has changed with the water or lighting. Any ideas? Thanks...

 

[bang guy]

What are you feeding your Pencil Urchins?

 

[flapjak68]

There's been a mild to med amount of greenish-brown algae in the tank for about 4-5 months and everybody in the tank (2 Percula clowns, 1 coral banded shrimp, 1 starfish) gets the Emerald Entree frozen food (krill, plankton, spirulina, etc.) This is a 20 gal tank btw...

 

[bang guy]

I believe Pencil Urchins are carnivores so they will need meaty seafood like squid, snails, clams, shrimp, etc.