Did you observe if your zoanthids that he was on had any spiders?
I'm just asking because I had a teddy bear crab that I pulled from my acro colony after letting him stay there for about a year. I kept him in a bucket until I can find someone that is willing to give him a good home.
Well, I found some zoanthid eating spiders, put them in front of him and he immediately grabbed the spider and tried to eat him.
I think the spider was way too big, and I saw him put it down.
I left them in the bucket with them and don't know if he ate them or not.
So, I'm just curious if you may have any spiders on there.....on the chance that they might eat these guys. (I am NOT insinuating that you would have them, just hoping to find something that would eat them....not that the crab is all much better to have I suppose)