Tiny B&W Snails

[strider]

I've just noticed a few small conical shaped snails, they are black and white smaller than a match head,
I looked for an ID but havn't found one, when they move they are very quick and look like tiny Nassirus snails?
Can anyone shed some light on them, are baby Nassirus snails like this, i do have a good number of these in my tank.

[Therbligs]

Picture would help.

[strider]

sorry they are in and about the reef and im not really able to catch, however i will try