In my tank, the blue legs have killed astrea snails, the red legs have not, and both have climbed gorgonia, ricordia, and hard corals without doing the corals any apparent harm. I'm still on the fence about the trend away from hermits. I recently bought some nassarius. After I got a shipment of predatory whelks by mistake and finally eradicated them, the nassarius have done a nice job of eating excess food off the substrate. But they don't climb and pick algae out of the crevices between the rocks and corals the way the hermits do.