Here is my "Really Uneducated Guess" about why Pleurotomaria have clean shells
(remember, this is coming from a severely land-locked person who knows didley
about shells, although I'm reading)....
Since they are deep-water they live below the photic zone, it's too dark to see
and therefore they do not require a visual camouflage.  Perhaps also, the type
of encrusting organisms usually associated with shells in shallower water shun
this deep water.
To really test this I would have to find out if other deep water shelled
molluscs have encrustations or not.  Does anybody know?
By the way I think James has done a great job on his site.  I also think
Andrew's suggestions for James are excellent.
 
 
Andrew K. Rindsberg wrote:
 
> Dear James,
>
> I just took a look at your Pleurotomaria website, which is quite
> impressive. You've done a fine job of putting together some interesting
> photos, all of which are properly attributed to the photographers. The
> living shells are gorgeous. The photo of a gold-colored snail eating a
> yellow sponge is a real winner.
>
> Some constructive criticism:
>
> You might consider adding some "Further Reading" on Pleurotomaria. I know
> that people have been sending you this kind of information. I'll help out
> with getting the references into a consistent style if you want.
>
> I find the emphasis on the money value of the shells to be a bit
> distracting, especially next to photos of living mollusks. These are, after
> all, creatures living with their own goals, not just things for us to buy.
> Maybe all the information on values could be gathered into one section or
> table by itself.
>
> And a question for the Conchlers: Living Pleurotomaria seems to have a
> perfectly clean shell without the usual encrusting fauna. Why?
>
> In sum: James has posted a useful report on Pleurotomaria and thus
> certified himself as a true Pleurotomaniac.
>
> Andrew K. Rindsberg
> Geological Survey of Alabama