Buzz
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1. Bezoars
In Harry Potter and the Sorcerer’s Stone, Professor Severus Snape revealed that “A bezoar is a stone taken from the stomach of a goat, and it will save you from most poisons.” While it may sound absurd, Snape wasn’t entirely off the mark. A bezoar is akin to a pearl formed in the stomach: An animal consumes something indigestible, and mineral salts accumulate around the object, eventually forming a stone.
In the Middle Ages, bezoars were prescribed by doctors as a remedy for poisoning. Consuming or wearing these mystical stomach stones as jewelry was a widespread practice among the wealthy and powerful, who often feared being poisoned.
Human bezoars develop without the hard outer layer, but they come in various types: phytobezoars (composed of undigested plant material like sunflower-seed shells), pharmacobezoars (formed from unabsorbed medications), and, most frequently, trichobezoars, or hairballs.
2. Otoliths
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Tiny stones, known as otoliths, are present in your ears. These minuscule calcium carbonate structures (commonly referred to as chalk) play a crucial role in spatial orientation. When you move your head, the shifting of these otoliths sends signals to your brain, helping you maintain balance and understand your position and motion. It’s a significant responsibility for such small stones.
Nearly all vertebrates possess otoliths, and researchers have found numerous applications for them in scientific studies. For instance, the age of a fish can be determined by examining its otoliths. Space agencies have sent various animals into space, observing their otoliths to assess their adaptation to zero gravity. (Spoiler: They struggle with it [PDF].)
3. and 4. Kidney Stones and Gallstones
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The mere mention of these can make some people shudder. Similar to bezoars, kidney stones develop when an excess of a particular substance accumulates in the kidneys. The most prevalent type is composed of surplus calcium. When urine becomes overly acidic, often due to a diet rich in meat or shellfish, uric acid stones can form. Their size, shape, and the discomfort they cause vary widely. Some individuals pass kidney stones without noticing, while others may require hospitalization.
Gallstones, on the other hand, range in size from a grain of sand to a golf ball. They consist of solidified cholesterol and bile deposits. While the exact cause of their formation remains unclear, one thing is certain: no one desires them.
Bonus: Gastrolith
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The term “gastrolith” refers to two distinct types of rocks, neither of which are found in humans, but both are fascinating.
The first type of gastrolith can be any rock deliberately consumed by an animal. Crocodiles, seals, whales, birds, and even their dinosaur ancestors have been observed intentionally swallowing rocks. Initially, scientists theorized that these creatures used the stones as ballast to prevent themselves from floating to the surface. However, recent studies suggest this would require swallowing an impractical amount of rocks, which they clearly do not.
Bird gastroliths serve a more straightforward purpose. Birds store these rocks in a gizzard, a specialized pouch. Since birds lack teeth, the gastroliths grind their food, aiding digestion before it reaches the stomach.
The second type of gastrolith is entirely different but equally remarkable. These are small nuggets or disks of calcium carbonate found in freshwater crayfish. Crayfish molt frequently, shedding their shells multiple times in their lives. Before molting, calcium from their shells forms these gastroliths. After shedding their old shells and before their new ones harden, the crayfish are soft and vulnerable. They reabsorb the calcium from the gastroliths to hasten the hardening process, acting like natural supplements. Unsurprisingly, humans once believed these gastroliths possessed magical or medicinal properties.
