tiny shells in gravel

Question
I bought some used gravel from a guy yesterday and when I rinsed it out this morning, hundreds and hundreds of these teeny, tiny cornucopia-shaped shells floated to the top; the more I swished the gravel, the more came up. I do mean TINY! I have no idea what they are but I  washed the gravel over and over. I'm certain I didn't get all of them. Do you know what they are?

Answer
Hi Rachelle,
Those are the unique shells of Malaysian Trumpet snails!

See here-
http://aqualandpetsplus.com/Bug_S96.jpg

They are very tough little critters and populate an aquarium very quickly from just a few individuals. They aren't really pests. More like helpful scavengers in a tank and they don't eat live plants either!

Sometimes they can seal themselves inside their shell and survive dry periods so its always possible you may have some live trumpet snails in your tank. But generally the ones that float -usually- are empty.

I hope this helps!!
Karen~