I bought a condilactis anemone a month ago,and since then the arow crab always stay beside her,touching her like it was is girlfriend or something!!I find it realy odd!!
He's established his "safe zone" He knows nothing is going to sneak up on him through the anenome so he hangs out by it. he touching it to make sure its still in place. Arrow crabs commenly find safe zones that prevent others from surprising them.