In an effort to know more than I need to know abour opercula, I have a
question:

I am familiar with the various growth patterns of opercula, but am at a
mental loss as to the techniques the shells use to add chitonous or
calcareous layers onto an operculum.  It is done by the mantle which
adds shell and periostracum to the growth edge of the shell, but it
stretches my imagination as to how the mantle maneubers itself
--
                     Aloha from Wesley M. Thorsson
Editor of Internet Hawaiian Shell News, a monthly Internet Publication
           122 Waialeale St, Honolulu, HI  96825-2020,  U.S.A
       http://www.hits.net/~hsn   or http://home.att.net/~w.thorsson