My emerald anemone crab?
 

He hangs out under there all the time. I bought him to get rid of a little bubble algae (which he did in no time). He has quickly become one of my favorite tank inhabitants.

no attached photo

Oops...should be there now.

reply
 

Very cool. I've got a buddy whole could use a few of those.

Cool little guy. They are a blast, eh? Who ever said crabs were no fun?

Emerald crabs must be very hit and miss though. I've had the same experience as you did - made quick work of what I got him to deal with. I've heard that many get them and they just sit there, like lumps on bumps.

maybe also depend on how much food you feed into the tank which already filled up the crab stomach and no more room for the green algae.. .. The crab will be oh.. I just need to stay here and the food will be falling down and eat it without need to look around for veggie which got no taste =)