Lots of Snails?

[swivel]

Recently I've been noticing i have a whole bunch of snails in my tank. Funny thing is that i didn't even buy any. They only come out at night, does anyone have any idea what kind of snails they are? and if they are harmful or not to my corals?

 

[charlesr1958]

Need some good, detailed photos of your snails to have any chance of making an ID. Thanks.

Chuck

 

[cloak]

My guess would be collonista snails. Here's a good article.

http://www.reefkeeping.com/issues/2004-05/rs/index.php.