Yes, in the ones I observed this was exactly as you describe. Guido.
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> From: Nancy Smith <[log in to unmask]>
> Reply-To: Conchologists of America List <[log in to unmask]>
> Date: Wed, 24 May 2000 17:12:38 -0400
> To: [log in to unmask]
> Subject: Re: bones, teeth, humans and molluscs
>
> So when a Cypraea's mantle is exposed, is the animal then completely, or
> nearly completely, outside of the shell?   And also when it withdraws, can it
> tuck all of it's soft parts inside the safety of the shell?
> Nancy
>
>
>
> Conchologists of America List <[log in to unmask]> wrote:
>> I have never read why, but when you look at a cowry with expanded mantle,
> and considering the animal is going completely (at least in the species I
> observed), then one may think the teeth guide the mantle and the animal to
> withdraw perfectly in this tiny hole. Probably there are cells in the mantle
> that detect the correct teeth, so very quickly it can withdraw in the
> correct way, better than if there were no teeth.
> Note: Ovulids most often do not have the teeth, but frankly I think Ovulids
> do not withdraw the animal often. But also most Trivia and Erato have them.
> Other ideas ?
>
> Guido
>