For small shells there are stand-lens, magnifier, with a scale in mm that would measures up to 40 mm or more.
You can put the stand-lens upon the shells to measure.
Helmut


Helmut "Helix" Nisters
Franz-Fischer-Str. 46
A-6020 Innsbruck / Austria / Innsbruck
phone and fax: 0043 / 512 / 57 32 14
e-mail: [log in to unmask]
web:    www.netwing.at/nisters/
           (please visit it and sign guestbook)

office:
Natural History Department of the
Tiroler Landesmuseum Ferdinandeum Innsbruck
Feldstrasse 11 a
A-6020 Innsbruck / Austria / Europe
phone: 0043 / 512 / 58 72 86 - 37

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Linda,

Amway used to make a rust remover.  I think they still make one under a
different name.  It is a bit acidic so temper the mixture with a bit of
baking soda.

Tom E.

> Hi, Everyone!
>        Thanks for the info on calipers.
>
>        Now I have a new problem - how can I get rust off a small shell.
Some exhibits ago, I mounted some miniatures on pins to make them more
visible.  Unfortunately, some of the pins rusted.  I have a golden yellow
Stomatolina rubra (Lamarck, 1822) that I want to mrescue!
>
>                         Thanks again,
>                                 Linda
>