I have several individual palys like that which were hitchhikers on my LR. They roll in their edges when disturbed by the crabs or fish, and sometimes it does take them quite a while to open back up. Some of them are kind of a drab brown color, but several have the pretty green inside. Mine seem to like bright light and those that are closer to the light are doing better than those lower in the tank. I don't feed them, and they are growing.