Can anyone give me some guidance on what I can do about my Emerald Crab?

He has been a great addition to my tank and haven't had any problems with him(have had him for about 3 weeks) but recently he started pulling my zoanthid polyps off the rocks and tossing them. so far I have had to rescue 24 polyps and am running out of space for frag plugs and other rocks that I can put them on. The tank has plenty of algae, copes, etc for feeding, plus I supplement with weekly feedings but nothing has stopped him from doing this. He only seems to do this on one particular rock and hasn't touched anywhere else. I hate to relocate the rock if it is a territory issue because the zoanthids are pretty happy where they are and I am limited on where I can put them with the right water movement and light (tank is a 29 Biocube). Any suggestions?


V/R,

Jason