> I know, because somebody told it here, that the reason why Cipraeidae and
> other families looks so glossy is the continuous contact between the shell
> and the body of living animal, but could anybody explain why is this
> contact?
What I tell people is, "would you like to have a lumpy, sandy bed?" The
animal prefers a smooth surface to spread its mantle on.
Some shells, such as Olives, not only spread their mantles over the shell
but also burrow. The smooth shell makes burrowing easier, as does the bullet
shape.  Burrowing shells with knobs and spines prefer to bury and stay in
one place, and the protrusions help anchor them; smooth ones move along just
under the sand's surface in search of prey.

Peggy
                     Visit my website at http://www.shelltrips.com
                                  Peggy Williams
                                   Shell Elegant
                                    PO Box 575
                                Tallevast FL 34270
                                   (941) 355-2291
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