Chances are they were hitchhikers on your plants, snails are very good at remaining hidden for long periods of time.
Try placing a piece of lettuce on the tank bottom at night, in the morning it should be covered in snails, simply remove the lettuce and any snails with it.
Best to do it soon though as they can multiple very quickly.
Try placing a piece of lettuce on the tank bottom at night, in the morning it should be covered in snails, simply remove the lettuce and any snails with it.
Best to do it soon though as they can multiple very quickly.