Glossopetrae: From Tongue Stones to Shark Teeth
Imagine yourself stumbling upon a jagged triangular stone glinting in the Mediterranean sun, with its sharp edges hinting at a mysterious past. What you’ve just stumbled upon was once known as glossopetrae or “tongue stones”. For centuries, people across Europe believed these objects were the petrified tongues of mythical serpents or dragons. Glossopetrae had been worn as amulets; ground into medicinal powders; even revered as talismans as these curious objects carried tales of magical or divine power. However, the truth behind glossopetrae is even more remarkable: today we recognize glossopetrae as ancient fossil shark teeth that have been buried in the Earth for millions of years.
A Mythical Beginning
In the Ancient Mediterranean, ranging from the rocky shores of Malta to the bustling markets of Rome, glossopetrae were objects of wonder. Their name is derived from the Greek words glossa (tongue) and petra (stone), reflecting their striking shape—pointed, serrated and eerily tongue-like. To the people of classical antiquity, these were treated as no mere rocks. In Malta, locals believed these peculiar fossilized stones were linked to Saint Paul’s legendary shipwreck on the island around 60 CE. According to the tale, Saint Paul survived a venomous snake bite, rendering all snakes harmless. This event tied to faith has led locals to associate the fossilized tongue stones found in Malta’s cliffs with his miraculous act. Though no archaeological evidence supports this legend directly, it remains a blend of cultural storytelling and natural curiosity that shaped their views on glossopetrae.
Elsewhere, the Ancient Roman naturalist Gaius Plinius Secundus (otherwise known to many as Pliny the Elder) spun a different tale in his Naturalis Historia (77–79 CE). Pliny the Elder speculated that glossopetrae were gifts from the heavens, falling during lunar eclipses and somehow resembling crescent moons. This enchanting idea highlighted the ancient tendency to attribute cosmic origins to mysterious objects. Across cultures, glossopetrae were prized as charms to ward off misfortune, cure snakebites and neutralize poisons. Nobles wore them as pendants, and apothecaries ground them into powders for antidotes, having been convinced their serpentine origins held potent magic.
The Truth Beneath the Myth
For all their allure, glossopetrae were not actual tongues, nor did they rain from the stars. As revealed earlier, these objects were the fossilized shark teeth formed millions of years ago, primarily from the Cenozoic era (66 million years ago to present). However, fossilized shark remains can extend across other geological periods, reflecting sharks’ extensive evolutionary history. Sharks, including Megalodon, shed thousands of teeth over their lifetimes, many of which sank into ocean sediments and fossilized into calcium phosphate. These shark teeth—ranging from small daggers to hand-sized giants—washed ashore or were unearthed in places like Malta, Italy and North Africa, where they puzzled ancient peoples’ minds.
The connection to sharks remained obscure for centuries, as most people in antiquity and the Middle Ages struggled to conceptualize these stones as remnants of living creatures. While some philosophical traditions speculated that fossils grew spontaneously or were shaped by natural earthly forces, others proposed more naturalistic theories, such as petrification through fluids. It wasn’t until the Renaissance that scholars like Konrad Gesner and Nicolaus Steno replaced myth with evidence, laying the scientific groundwork for paleontology.
The Renaissance Revolution
In the 16th and 17th centuries, a wave of curiosity swept through Europe, and glossopetrae became a focal point for scholars eager to decode nature’s secrets. One of the first to challenge old beliefs was Swiss naturalist Konrad von Gesner who noted the striking similarity between glossopetrae and modern shark teeth in the 1550’s. His observations planted seeds of doubt about their mythical origins.
The decisive breakthrough came in 1616, when Italian scholar Fabio Colonna published Dissertatio de Glossopetris. Comparing fossil teeth to those of living sharks, Colonna argued convincingly that glossopetrae were not serpent tongues but rather ancient shark remains. His work established the base for a scientific revolution.
The most focal moment then occurred in 1666-1667, when renowned Danish anatomist Nicolaus Steno received a massive great white shark (Carcharodon carcharias) head from the Grand Duke of Tuscany. As Steno dissected it in Florence, he detected an astonishing find: the shark’s teeth were identical in shape to the glossopetrae he’d studied. In his groundbreaking work during, Canis Carchariae Dissectum Caput, Steno declared that these “tongue stones” were thus fossilized shark teeth. His findings demystified glossopetrae from their mythical origins, and instead proved that the fossil teeth were remnants of long-extinct life that once swam the prehistoric oceans.
Steno’s work, alongside contributions from others like Fabio Colonna, helped birth paleontology. While figures like Leonardo da Vinci had speculated about fossils’ marine origins and Robert Hooke had explored their organic nature, it was Steno’s meticulous evidence that turned the tide. From this point, human understanding evolved from fantastical speculation into scientific fact.
A Legacy of Wonder
The story of glossopetrae is more than a tale of mistaken identity—it’s a testament to humanity’s quest for truth. From Maltese cliffs to Renaissance dissecting tables, these fossilized shark teeth have captivated imaginations for millennia. Once revered as divine relics or cosmic gifts, they now stand as evidence of ancient oceans teeming with predators like the Megalodon, whose massive teeth likely numbered among the glossopetrae treasured by our ancestors.
Today as we celebrate Shark Week, glossopetrae remind us how curiosity and evidence can transform myth into knowledge. They invite us to marvel at the creatures that ruled the seas millions of years ago and to celebrate the thinkers who dared to question ancient tales. So, the next time you hold a fossilized shark tooth in your hand, imagine the journey it’s traveled—from an ancient ocean to a medieval amulet, and finally to a symbol of scientific discovery.
Header Image: Fossil shark teeth of various shapes and sizes. By Luca Oddone. Source: CC BY-SA 3.0.
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