**Malaysian Trumpet Snail** That is not it's scientific name, but their common name.
It's a common snail in the Pet trade. It is not always seen because of it's habit to burrow into the gravel. If you turn your lights on one night, you may find a lot more than you had ever thought you had.
They can be a good snail to have, as they will take care of a lot of uneaten food, turn-over the substrate and keep it moving and if you happen to have a fish die unnoticed, they will eliminate it before it fouls your water.
They gives birth to live babies so you will not find any eggs.
Unfortunately, I accidently deleted a lot of the info I had on these snails and now have to go do more research. sorry