Yup. I found that out when I got my first Pleuro
and the Pleuro book. Kind of interesting how they
retrofill the slit.

Andrew Grebneff wrote:

>
> I suspect Emilio knows... but for those who don't.....cut....
> Living taxa: Pleurotomariidae,
> most Scissurellidae, slit Fissurellidae, some "turrids". The
> selenizone is the track left by the slit as the shell grows by labral
> accretion, and is often bounded by raised cords or lirae.
>