But pearls and Corrall, and whatsoever else hath a saxatile hardnesse of shell-fish, must give place truly to gemmes for hardnesse; and yet they are not therefore digested in the Athanor of our Oeconomy, so well as in the stomack of some birds. But the stones of Bezoar and of Crabs &c. not so hard as pearls, are not of a saxatile nature: but are rather made of a lacteous semi-caseate & semi-petrified juice, and have a neutrall nature of a tophe, between a Cartilage and a stone.