I have found that Yellow Coris, Leopard, 6 and 4 line as well as Mystery Wrasses will eat all small snails (including pyram) as well as flatworms, small nudibranches (think harmful) and other small pests. They could eat enough pods to starve an existing mandarin, so be careful.
I eventually hated the 4 and 6 lines because they were hostile toward new tankmates, but they were excellent eaters or unwanted organisms.
My new favorites are the leopard wrasse family. They "get up" at about 8 AM while the lights are still off for a while and hunt pods and stuff. They "go to bed" about 9:00. Their bellies are always full, even when I don't feed for some reason.
I would do more research on mystery wrasse before you depend on one, but it worked for me... not saying that it will work for you. The others are commonly known for eating pyram.