For fun I would like to hear about things that people have found on their rock later after being placed in their tanks. For me the worst was a mantis shrimp, for months I would hear that thing click at night and I had coral banded shrimp and other animals dying ( disappearing ), I finally caught the thing after I seen in go in to a rock and he got a fresh water dip. The best hitchhikers I had was a rock with a mess of these red and yellow tube or rock worms, they were small, but very beautiful. ohhh! and a small some kind of gorgonian.