Saw one of these today on my second dive. Was with a large group of divers who had stupid amounts of gear and a full on camera man. I waved him over when I spotted it, but he culdnt see it and started filming a rock before swimming off disinterested in said lifeless rock. I stayed and watched the "black lionfish" for a few minutes before the camera man came back past, kicked the fish with his fins as he did so, and then finally saw it and got excited, called his mates over with some clever underwater signal and the fish became a sub aqua niomi Campbell for a while.
Picture from www.thescorp.net