For human beings a periostracum might be not of aesthetic, but many have a
higher worth with periostracum.
Look maybe at a Cymatium parthenopeum. Without  periostracum it looks very
very poor and bald heated,
but how splendid is that shell with his hairy and dark periostricum. But
not all shells have a periostracum
compact like this. I find it is a pity when the collectors will clean the
shells from the persiostracum. In many
cases I find it much more interesting to conserve the periostracum on the
shells. But many collectors want
to have a clean shell in their collection for aesthetic. What is a brown
Syrinx against a orange-yellow one.
It might be that shells with periostracum are not such aesthetic, but they
are more interesting.
And many wives will find some men with hairs more interesting than without.
(Only a joke to cover the
periostracum question.)
with best shelling greetings.
Helmut from Innsbruck

Helmut "Helix" Nisters
private:
Franz-Fischer-Str. 46
A-6020 Innsbruck / Austria / Europe
phone: 0043 / 512 / 57 32 14
e-mail: [log in to unmask]
website: www.netwing.at/nisters
office:
Natural History Department of the
Tiroler Landesmuseum Ferdinandeum Innsbruck
Feldstrasse 11a
A-6020 Innsbruck / Austria / Europe
phone: 0043 / 512 / 58 72 86 - 37
e-mail: [log in to unmask]
website: www.tiroler-landesmuseum.at


----------
> Hi Wesley,
>
> I'm no expert (that's for sure) but I'll bet that for some species (like
> hairy tritons) the periostracum serves as camouflage. No doubt some
potential
> predators hunt visually. If this is so, why they happen to have such
splendid
> markings underneath is baffling.
>
> But as for beauty, I think it is the beachcomber or shell collector who
> appreciates the beauty of shells. Aesthetics are, I'm thinking, a human
> thing. And if I'm wrong, who is to say what mollusks consider beautiful?
They
> make admire the beauty of slime and hairy periostracums. They might find
> their glorious shells (no matter how natural) unattractive and
embarrassing,
> like we do male pattern baldness or facial hair on women (also perfectly
> natural).
>
> Ellen (in a silly moment)
>