I have lots of chitons, sponges, and some limpets that I think are cool. As far as free coral there are a couple green button polyps, brown porites, neon green porites, and some kind of lime green/yellow sps (still tiny) has started growing where a live rock harvester sawed off a coral. Oh, and I really like the calcarous macroalgae too. As far as a favorite one, I like the chitons the best but that sps might be the best when bigger.