Help with ID please

[mdb_talon]

I have what seems to be small black and white spiral snails. I found one each of the past two nights crawling on a zoanthid. Mostly want to see if it is harmful and googling has not helped me find what this is.

Picture attached and here is link to larger picture that shows it in context.
http://i467.photobucket.com/albums/rr40/mdb_talon/IMG_0129.jpg

 

[Kevin8888]

I would say it looks alot like a snale from the Heliacus group and they are zoe preds so get rid of them if u want to keep your zoes.
http://www.chucksaddiction.com/Hitchsnails.html has pics of the snale I'm talking about so you can check for yourself.

 

[Myteemouse]

looks to be those

 

[mdb_talon]

Thanks a bunch that looks like them. Bought some large colonies of zoa this past weekend. Luckily still in QT tank. Have found several so far now looks like they will be in QT awhile.