There has been quite a bit of discussion lately about identifying
juvenile molluscs, but can anyone tell me, are there any examples of
extant molluscs that exhibit noticeable sexual dimorphism.  I have never
seen any examples of this in the shell books that I currently have
access to.
This was quite prevalent in fossil ammonites (Mollusca-cephalopoda), the
recognition of which has led to substantial revision of the taxonomy.