Lapidifying virtue diffused through the whole body of the geocosm

"While examining the teeth of the shark, Steno was struck by their resemblance to certain stony objects, called glossopetrae or "tongue stones," that were found in certain rocks. Ancient authorities, such as the Roman author Pliny the Elder, had suggested that these stones fell from the sky or from the moon. Others were of the opinion, also going back to ancient times, that fossils naturally grew in the rocks. Steno's contemporary Athanasius Kircher, for example, attributed fossils to a "lapidifying virtue diffused through the whole body of the geocosm." Steno, however, argued that glossopetrae looked like shark teeth because they were shark teeth, that had come from the mouths of once-living sharks, and come to be buried in mud or sand that was now dry land. There were differences in composition between glossopetrae and living sharks' teeth, but Steno used the "corpuscular theory of matter", a forerunner of atomic theory, to argue that fossils could be altered in chemical composition without changing their form."

- Nicholas Steno (1638-1686)