Hi Andrew

Yes, no doubt it is eroded, but I can't quite understand the dislocation of the line as it was
melted.

If you grind a shell it will not look like this, the shoulder line will not be displaced.

Marcus




Hi Marcus

The shell has been severely eroded on tle lower surface. I think this
will be because the animal was geronitic and had stopped growing,
hence the shell has been exposed to abrasion on the final underside
(remember the shell rotates around the coiling axis as it grows, but
ceases rotation at cessation of growth) long-term.

I have noted a smooth eroded patch behind the aperture in a number of
largish Recent & fossil operculate shells (eg Penion, Pleuroploca)...
these specimens had ceased growth and the shell had become worn where
it rested on the operculum during the snail's activities.
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
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Seashell, Macintosh, VW/Toyota van nut


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