i have my peacock that is about 4-4.5 in with an urchin, 3 damsels, feather duster, torch coral, xenia coral, sally lightfoot crab, red leg hairy hermit, and im 95% sure that he just hasent had the opportunity to get them by surprise.
i have seen the urchin with some broken spins so im sure thats how he is making it passed. the damsels are to fast. he would have to catch them by surprise. hermit has a good shell. the sally has been hiding inbetween the rocks. feather duster and the 2 corals dont phase him.
i doubt my mantis would go for a sea star. only because most of the time the star would be in the rocks pretty tightly. IMO