Need a id on these snails please

[Ssteve]

Had about a million of these pop up in just a few weeks and wondering what they are. Haven't seen any on corals or anything so I'm assuming they aren't bad.


http://i69.photobucket.com/albums/i45/ssleevin/th_0E2B9508-69F4-4ED2-8819-C9B6E09245AA-2901-00000256FC3B4158_zps6a9b50b2.jpg (http://s69.photobucket.com/albums/i45/ssleevin/?action=view&current=0E2B9508-69F4-4ED2-8819-C9B6E09245AA-2901-00000256FC3B4158_zps6a9b50b2.jpg)



http://i69.photobucket.com/albums/i45/ssleevin/th_C8284D61-D26B-4BC8-9250-914244A14BA5-2901-00000257044787A5_zpscd218e71.jpg (http://s69.photobucket.com/albums/i45/ssleevin/?action=view&current=C8284D61-D26B-4BC8-9250-914244A14BA5-2901-00000257044787A5_zpscd218e71.jpg)

[JB63]

look like limpets, very beneficial in a reef tank.