I have one in my tank, only see him/her at night when I feed the acans. At one time I saw it under the acan rock bench pressing the rock up and down. Later that day the acan rock was on the sand bed upside down. Aside from that I've never had problems with them. Like Rob though I'm seriously thinking to get rid of my hermits as I've never seen so many empty snails shells in my tank.

Just a little off topic, but is the salifeet crab any better/worse than the emerald?