Creature Identification

[Razorburn26]

I purchased some live rocka bit ago and wow the stuff that came off of it. One of the little things i just cant identify. It is about 1/4 inch long. Almost like a white slug with a small oval shell on top. Moves like a slug also. Looks like it spits dust or sand at times. any help would be apreciated. Thanks

[T Man]

Could be a small limpet, it's hard to tell from just the description. If it is a limpet, and you have an acrlyc tank - it will scratch the snot out of your tank. Tinman