I've also had difficulties with Haliotis (if you leave them in bleach too
long, the interior will get clouded) and Calliostoma (very small fragile
ones might even get 'eaten up').  Since then I very thoroughly coat any
mother-of-pearl with petroleum jelly before they go into bleach, and watch
anything with nacre like a hawk.
Otherwise bleach never did any damage, even in rather prolonged exposure.
Monika