Dear Paul,

I am not familiar with mautitiana, but I have seen a (probably) similar phenomeon in annulus.
As the shells get older, its shell surface became cloudy and whitish that often made the orange
ring invisible. This is based on our observation on individually marked shells in the field.
I suspect that the older shells excreted surface cover with irregular crystal layers that
might scatter light in random directions, so that the nacreous layer was lost underneath.
We may be able to verify this hypothesis by cutting shells to examine micro-structures, but
It may require a SEM.
Masashi Yamaguchi
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Sent:   Wednesday, February 09, 2000 11:49 AM
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Subject:        Cowrie question

Does anyone know what causes the cloudy, or slightly "milky" appearance that
is so frequently seen on the bases and low on the sides of Cypraea
mauritiana?  Some of them have clear glossy black bases, while others have
that "cloudy" appearance.  Is it natural, or the result of improper cleaning?
Paul M.