What snails are bad?

[cjsiii]

Does anyone know a link to something describing what snails are bad in my aquarium?
I know the new snails that have popped up are not sundial snails, which i know are bad, but to find out exactly if i should leave them or yank them.

 

[hlcroghan]

if you have ones that are in your tank that you are specifically asking about you should prolly take a pic and then someone can tell you what they are. Most snails we get here are good ones I believe. You could also look at some of the ones they have for sale here and see if you see a resemblance.

 

[au mister]

sundial snails are bad and they will eat your polyps. They are black and white.