I agree they're all nassurius. The nassurius that I have are the rougher shelled version in your photo, but I often see that light colored one with the smoother shell sold as nassarius in stores.
I've had them 6 years, yeah I didn't know snails lived that long either, and they do nothing harmful. If anything dies in the tank, they are right there and remove it before it decays. I think people suspect them of killing whatever it is that died, but they just respond quickly to feed and but didn't actually kill anything.