Need Snail ID help!

[OneReef]

I have looked around the internet but can't seem to find out what snail I have in my tank. There are thousands! of these little snails in my tank, mostly coming out at night. They are very tiny, like the size of the end of a ballpoint pen. It doesn't seem to be a hatching of larger snails because they stay this size and have been around for months and months. At night, they cover my rocks and are hundreds covering all sides of my glass. They kinda scatter into hiding when the lights are on. I see them on the rocks in the day, but not as prevalent like at night. Here is as good a picture as I could get: Any help? Good, bad? Any way to remove if bad? I really need an ID.
http://i43.photobucket.com/albums/e370/topgun121/snail1.jpg



Here is a picture of their backs, on an envelope letter for scale size:


http://i43.photobucket.com/albums/e370/topgun121/snail2.jpg

[Sugar Magnolia]

It's a harless collonista snail. Great little nocturnal janitors.

[MARINECRITTERS]

It's a harless collonista snail. Great little nocturnal janitors.

+1, I have tons in my tank ( they are always reproducing at night )

[Musing.Dog]

I love these little guys. I have tons as well; definitely collonista. They go all over the glass eating film and soft algae, not to mention they are adorable. They stay pretty small too. Awesome addition, imo.