Mystery of the Snail Shell

[EverythingIsTicketyBoo]

So I have 2 snails in my tank, they've been there since February when we set the tank up.

I put the light on yesterday and found a shell floating on the water, clearly empty and definitely the right pattern for one of my snails, I had a look around the tank to see of the other snail was ok, and found both snails Any ideas where this rogue shell might have appeared from?

The random empty shell and my 2 snails very much still alive.

Well, they are nerites so you can rule out any sneaking breeding. They can tuck themselves away and float around, was the shell definitely empty? Did you see all three at once? Sometimes you can get shells coming in with gravel or in plant pots.

Hmm I suppose it's possible one sneaked in on a plant, I have only ever had 2 so I wonder if I just never noticed a 3rd one after checking 2 are alive and well it is definitely empty, I left it in the tank just in case and it was still floating about when I did the water change (just finished doing it) so I've taken it out now and had a good look. I can't believe I b never noticed a stowaway snail!