I respectfully disagree with laks..... I have 2 bumblebee snails in my 29 gallon tank. I've had them for well over a year now. They don't come out much, but when they do, I enjoy the beautiful markings on their shell. If you feed like I do, everyday, they are a valuable part of a cuc. They eat any left over food off of live rocks and can get in small crevices because of their size. Mine have been model additions. As far as them eating any sand dwelling worms, I have not seen them do this as they spend most of their time on the rocks. If they did consume some worms, I'd welcome it. I have an over-population of bristle worms anyway.
Here's more info on them:
http://www.liveaquaria.com/product/prod_di...&pcatid=565