What are these snails?

[Giang]

My tank has been setup for almost 5 months. I have 2 turbo nails to clean up the brown algae and yesterday i noticed there are a few little snails but i'm not sure where these come from and are they good or bad?

 

[KJ]

Hard to tell from the pic. Google Collonista snail.
https://www.google.com/search?q=col...-TC58Q_AUIBigB#safe=off&tbm=isch&q=collonista

 

[Lovemyreef2015]

+1 collonista snails. Good cuc