Snail identification?

Here is a picture of one of them. They are 3/4" long and bury themselves in the sand during the day...at night they all come up and are quite active....very fast moving. They have that little foot thing sticking out of their head like a conch does. Any ideas?

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One of my favorite snails. I have 3 in my 10. They stay under the sand, with their tube extended above the surface, and erupt up when ever I feed.
 
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