Dear Paul

Thanks for the information on the shells. You are correct, the lighting on
the abalone
shell was with sun light focused with a 14" convex mirror and directed
through colored gel filters. This creates a very unusual iridescence. It is
not just a simple filter effect since there is a range of vibrant colors. I
have never been able to figure out the physics of the light effect. Do you
have any ideas?

Best Regards

Dennis Felty

Paul Monfils wrote:

> Hello Dennis,
>
> Welcome to Conch-L!
>
> I took a look at your pictures.  On the first page, 6 of the first 7
> pictures are of a pearled Turbo argyrostomus (silver-mouthed turban
> shell).  "Pearled" means that the outer layer of shell has been removed,
> to exposed the underlying pearly layer.  The second picture is also of a
> Turbo (turban shell), but I can't tell the species with certainty, from
> the rather limites portion of the shell that is shown.  It may be a
> small Turbo marmoratus (green turban), or it may be another Turbo
> argyrostomus.  This one is natural, not pearled.
> Pictures 8 and 9 on that page are of a bisected Nautilus pompilius
> (chambered Nautilus).  This is not a snail, but a cephalopod (a relative
> of octopus and squid).
> Pictures 10 and 11 appear to be of a pearled Turbo sarmaticus (South
> African Turban).
>
> On the second page, the top picture and the 2 bottom pictures are again
> T. sarmaticus.
> There is one more picture of Nautilus pompilius.
> The rest of them appear to show the inner surface of a large abalone
> shell (Haliotis).  Some of these show the natural pink/green
> iridescence, and were presumably photographed with white light.  Other
> views look like they may have been photographed while illuminated with
> colored light.  Is that correct?
>
> Regards,
> Paul Monfils