Dear John,  I also subcribed to the 'theory'  that the 'Cock's Comb Oyster'
Lopha cristagalli was the inspiration for  the design of the Sydney Opera 
House, as it was an interesting little anecdote for my shell talks.  Within
the last year however I watched an interesting BBC documentary on the
building of the Sydney Opera House, which informed us that the designer was
a mathematician, and the shape design was based on a complex mathmatical
formulae which he hoped would produce 'perfect' sound resolution.  Alas the
outcome did not live up to the 'purists' expectations.  The 'Cock's Comb
Oyster' I'm afraid did not even get a mention, much to my regret.  So I now
refer to the Guggenheim Museum, New York.as  the design of the entrance
hall I am told is,  loosely based on Thatcheria mirabilis.  Can anyone
support this comment or is it just another figment of some ardent shell
collector's imagination.  
 
Stanley Francis