>About formaldehyde, it can't be used in shinny shells (I tried once in small
>cowries and they were destroyed).

In my experience formalin diluted to 4% is fine for glossy shells
overnight or even a few days, but not for long-term storage. I
haven't used it on cypraeids but the inductura of any gastropod is
just as glossy as a cypraeid, and I haven't had any etching problems.
If suitably buffered (eg with sodium hexametaphosphate) there should
be no problems long-term either.

>Microwave is good in some cases - but never use it if the animal
>is rotten.

Any moisture-containing crack in a shell will be forced open in a
microwave as the water boils and exerts pressure within the fracture,
so I would hesitate to use this method. But if it works for others,
go for it. Knowing my luck, I'd have shell-bombs in my microwave if i
tried it!
--
Andrew Grebneff
165 Evans St, Dunedin 9001, New Zealand
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Seashell, Macintosh, VW/Toyota van nut