I just saw one of those at a local fish store, the guy didn't even know that he had it. My buddy almost got it but decided not to. But it was wicked cool to watch, it was only about 1/2" and was building istelf a cave out of snail shells.
i have one, its about 1.5in, yellow with striking red and white markings. it has formed a symbiotic relationship with my banded shrimp goby. really neat to watch too.