Lions or anglers won't go after hard bodied inverts. I never cared to put emerald crabs with my anglers for fear the emerald would pick on the angler. Anglers are very sedentary and emeralds can go rogue, but hermits are good. A tuxedo urchin is a great cleaner, I mean your rocks will sparkle. But unless the tank is large enough and mature enough to keep them in algae, they inevitably starve to death. You can keep an urchin in a smaller clean tank by feeding him strips of packaged algae/nori. I mean daily, these guys eat and eat and eat. And yes, shrimp is on the menu for lions and anglers. Ghost shrimp is actually one of the main foods you will feed them.