Reddit user Zu_Qarnine sparked widespread online discussion after sharing a photograph of unusual coastal stones featuring perfectly smooth through-holes drilled clean through them.
The user discovered the rocks while exploring a coastal zone and posted the image on the popular social media platform after becoming puzzled by the ideal, straight shape of the holes.
The post quickly attracted attention from online commentators, who put forward various theories to explain how the rocks acquired such uniform openings. One user suggested that ancient aliens might have been responsible for creating the clean drill marks.
Another user offered a different explanation based on family advice. The commenter shared that a cousin who is enthusiastic about geology suggested prehistoric reeds were the cause, proposing that clay had hardened around the plant material over thousands of years to leave the hollow openings.
Natural origin of witch stones
Despite the theories of extraterrestrial involvement or prehistoric plants, the unusual openings were actually formed by marine bivalve rock-boring mollusks. In certain parts of the world, the perforated rocks produced by these creatures are known by the ominous title of witch stones.
Bivalve rock-boring mollusks are marine invertebrates that use specialized anatomical features and muscular movements to excavate protective shelters in coastal shorelines. Stones naturally hollowed out by marine organisms or water erosion have a long history in coastal folklore, where they are also referred to as hag stones or adder stones and are traditionally associated with magic and protection.
One commenter provided a detailed breakdown of how the organisms shape the rocks. The user explained that the mollusks utilize their powerful muscles to bore into soft geological formations, such as slate or limestone, to carve out a secure burrow for shelter.
The same commenter noted that after the mollusk dies, ocean waves gradually erode the surrounding rock face over time. This continuous water action eventually transforms the inner burrow into a complete through-hole that passes entirely through the stone.
Folklore and previous beach finds
In addition to explaining the physical process, the commenter highlighted traditional beliefs connected to the stones. The user wrote that some people believe looking through the central hole grants the ability to see fairies or ghosts, while others believe carrying or displaying the stones can ward off bad luck.
The debate over the beach stones follows a previous sinister discovery along a shoreline that caused serious concern among internet users. In that earlier incident, web users were alarmed after speculating that a mysterious item washed up on the sand was a fragment of a human skull, which some suggested might have belonged to a child.
