I have a long spined urchin (echinometra viridis) that I hardly ever see during the day. He cruises out of his hiding spot just as the lights are going off in the evening, then disappears into some crevice for the daytime again (he's really good at hide-n-seek). So far I have only had one rock avalanch that I suspect he was the cause of. It took me over an hour to re-stack the rockwork and get everthing sitting solid again.
My coraline has been spreading very well with him in there. I was concerned for a while that he would not find enough to eat, since I have little algae other than the coraline, but he seems to be doing just fine. He's really cool when I can see him.
