I'd reconsider the position.  My experience with brittle or in specific -
glass.   One can hit it with a rock or ball peen hammer and it shatters.
Shoot it with a BB and a conical hole is produced.  A high force over
a small area can snap open a hole (e.g. a tooth point) whereas a broader
surface bends and shatters.

Martin

Andrew Grebneff wrote:
>> Curio shop Nautilus shells are frequently drilled by octopus, but I don't
>> recall seeing any with two octopus holes. To my knowledge, Marion Nixon
>> discovered shell-drilling by octopus (Journal of Zoology, 187:291-296,
>> 1979).
>>
>
> Holes made by octopuses are conical in section and are irregular in
> plan view. They may show radular scratchmarks around the edges. I have
> Oliva, Prunum ande Nautilus with clear octopus holes.
>
> Shells are brittle objects. Despite all the rubbish published about
> fossil ammonoids showing tooth-punctures caused by mosasaur bites, an
> shell will never show such damage... they can't. If something bites
> them the shell will BREAK. Pieces may be broken out, but they will be
> angular, never circular, and much more likely is that much of the
> shell will shatter. The thicker the shell, the larger the pieces` will
> be relative to the size of the shell.
>
> --
> Regards
> Andrew Grebneff
> Dunedin, New Zealand
> Fossil preparator
> Mollusc, Toyota & VW van fanatic
>
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--
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
"Our Republic and the Press will Rise or Fall Together": Joseph Pulitzer
TSRA: Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
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