Need help IDing this "thing"/snail?

[eastbayreefer2010]

Ok, so I was playing in my sandbed (looking for buried treasure) and I found this..... well, thing, I am not sure what it is, it has a yellow belly, black/white spots on it and only a top elongated shell.

check out this video and let me know what it is and if it is good/bad.

http://s291.photobucket.com/albums/ll315/All-Tech-Liquidation/?action=view&current=Snail.mp4

thanks

 

[nudibranch]

I think it is some type of Limpet or Cowrie.

 

[GreshamH]

Stomatella varia- snail - good thing (algae eater, breeds in tank)

http://www.reefcorner.com/SpecimenSheets/stomatella_varia.htm

http://reefkeeping.com/issues/2004-05/rs/index.php