Christopher Duffin
London, United Kingdom

Herbal and zoological materials have a rich and intensely studied history as medicinal simples dating from classical times. However geological materials, especially fossils, have received little attention in the literature. Although relatively minor components of the apothecary’s arsenal against disease, they nonetheless have a well-established pedigree as prophylactics and components of compound medicines. There are at least two pre-scientific apothecarial names for medicinal fossil fish teeth: “toadstones” and “glossopetrae” or “tonguestones.”

Toadstones are also referred to in the literature as lapis bufonius or crapaudine. Their name alludes to the belief that the stone was found in the heads of old, large toads. The stone could be extracted in one of several ways (Fig. 1A). According to Edward Topsell (c. 1572–1625) a living toad was to be placed on a scarlet cloth. Having a particular love for that color, the toad would stretch itself out on the surface and release the stone from inside its head. In order to prevent the toad from instantly retrieving it, the prospective collector was encouraged to force the stone through a concealed hole and into a bucket of cold water from which the toad was unable to recover it.¹ An alternative suggestion from Thomas Lupton (fl. 1572–1584) was to place the toad in an earthen pot, which was then buried in an anthill. The ants would strip the carcass, leaving the skeleton and toadstone untouched.²

Descriptions of the toadstone indicate that it varies in color, measures around 1.5 cm in diameter, is usually hemispherical with a concave underside, and occasionally has a central “eye” in the center of the convex upper surface. Figures of toadstones provided by Conrad Gessner (1516–1565) and Ole Worm (1588–1644) indicate that they were the teeth of Mesozoic bony fishes (Actinopterygii) belonging to the genera Lepidotes and Scheenstia (Fig. 1B).

Identification of the supposed therapeutic properties of toadstones relied on the Doctrine of Signatures. This theory stated that God has provided all the medicines needed by mankind in the natural world, giving clues as to their intended application by their (usually physical) characteristics. Toads possess dermal poison glands, and their warty dermal structures evoke the hemispherical shapes of the toadstones. Thus, the stone derived from the toad was deemed to be effective against poisons, including those engendered in the body by infections.

The size and shape of the tooth was ideal for setting as a cabochon in a ring where it could exercise prophylactic power against poisons by sweating or changing color in their presence (Fig. 1C). Alternatively, the toadstone could be taken internally. Here it “rolls about the Bowels, and drives out every poisonous Quality that is lodg’d in the Intes­tines; and then passes thro’ the Fundament and is preserved.”³ During its internal journey, the toadstone was believed to neutralize the poisons associated with, among others, malignant tumors, biliousness, abscesses, plague, malaria, fevers, labor pains, fits, scrofula, bowel problems, bladder stones, and epilepsy.⁴ An added benefit was that the stone could be recovered from the feces and reused.

The second type of tooth belongs to fossil sharks (Chondrichthyes). Pliny the Elder (23/24–79) ascribed a cosmic origin to these specimens, stating that they fall from heaven during an eclipse of the moon.⁵ Once again, it was Conrad Gessner who correctly identified their nature, this time by making direct comparisons of the fossil forms with the dentitions of modern great white sharks. The bulk of the fossils referred to as glossopetrae are the large triangular teeth of the gigantic mackerel shark, Otodus megalodon, mostly known from rocks of the Miocene epoch. Malta is a particularly rich source of these fossils and acted as something of an export hub to the apothecarial markets of Europe during early modern times. By the Doctrine of Signatures, tooth morphology resembled the forked tongues of snakes, particularly in the double-pronged nature of the root. This suggested that the objects were of particular use as alexipharmics in defense against poisons. Indeed, elaborate items of Renaissance tableware were kept on the credenza to provide a means of testing drinks for the presence of poison. A glossopetra could be removed from the (commonly arboriform) stand and dipped into the beverage; a change in color would have indicated the presence of poison.

Alternatively, the tooth might sweat as the food was brought to the table. In this way, the glossopetrae behaved in a similar fashion to toadstones.⁶ They were also worked into items of personal protective jewelry, especially pendants (Fig. 2A). Maltese examples were sometimes referred to as Ilsien San Pawl (St. Paul’s Tongues) in the belief that, when the apostle shipwrecked there in around AD 60, these remained as physical records of the force of his teaching in the island’s rocks. The locals prepared a decoction of the fossil by boiling it in a suitable liquid (water or wine) to extract the healing essence of the material. An alternative approach was to file small amounts of powder off the serrated tooth for addition to a suitable draught.⁷ One surviving specimen from the collection of a French apothecary is housed in a sumptuous red case (Fig. 2B); scratch marks are still visible on one face of the tooth where material was scraped off to provide therapeutic powder.

An additional application of fossil sharks’ teeth was in the production of synthetic alexipharmic preparations known as Lapis de Goa or Goa stones. These were bezoar stone substitutes produced according to a closely guarded recipe by Jesuit lay brothers in India during the late seventeenth and eighteenth centuries. Glossopetrae appear in one of the surviving recipes found in the Vatican archives. Other ingredients in this synthetic stone included medicinal earths, precious stones, ambergris, musk, and deer horn.⁸

References

1. Edward Topsell. The History of Four-footed Beasts and Serpents. London: J.R., M.D., & E. Cotes, 1658: 727.
2. Thomas Lupton. A thousand Notable things of sundrie sortes. London: John Charlewood for Hughe Spooner, 1579: 167.
3. Camillus Leonardus. Speculum lapidum. Venice: J.B. Sessa, 1502: unpaginated.
4. Christopher Duffin. “Fossils as Drugs.” Ferrantia (2008): 44.
5. John Bostock and Henry T. Riley. The Natural History of Pliny. Volume VI. London: Henry G. Bohn, 1857: 449.
6. Christopher Duffin. “Natternzungen-credenz: tableware for the Renaissance nobility.” Jewellery History Today 14 (2012): 3-5.
7. George Zammit-Maempel. “The Folklore of Maltese Fossils.” Papers in Mediteranean Social Studies (1989): 1-29.
8. Maria do Sameiro Barroso. “The Goa Stone: myths, empiricism and insights on chemistry.” Vesalius 26.1 (2020): 41.