"Welcome back, Question Man!"
Thanks. nice to BE back.
        I guess we've all seen two headed snakes and six footed calves. The
question is whether abberations in mollusks appear. We know that there
are "freaks" among shells. These are usually exterior and may have
nothing to do with the animal.
        It would be a guess that if abberations do appear, that they would be
wiped out in the juvenile stage, never growing to adulthood. Still the
malacologists among you may know of and be able to describe some chance
survivals among "freak" mollusks. Perhaps among the shell-less
mollusks---.
        The Question Man