A rock with an apparently embedded metallic screw found in 2002. Dismissed as a crinoid fossil by most geologists; embraced by fringe theorists as an ancient machine part.
An impossible discovery
On June 30, 2002, a Chinese collector named Mr. Zhilin Wang was exploring near Marzong Mountain on the border of Gansu and Xijiang provinces when he found a peculiar rock. The pear-shaped stone, measuring approximately 6 x 8 cm and weighing 466 grams, was exceptionally hard and had a dark black color. Remarkably, the object seemingly embedded within it: a cone-shaped bar, about 6 cm long, with distinct, evenly spaced screw threads.
The discovery gained media attention, published in the 'Lanzhou Morning News' on June 26, 2002. Initial examination by a group of geologists and physicists from various Chinese institutions led to speculation. The object's uniform threading and metallic look seemed to defy a natural origin. Theories circulated that the stone was a meteorite carrying an extraterrestrial artifact or a relic from a lost, technologically advanced civilization. Proponents of the "Out-of-Place Artifact" (OOPArt) theory pointed to the object as evidence challenging the conventional timeline of technology.
The geological explanation
Most geologists and paleontologists offer a different explanation. The "screw" is almost certainly the fossil of a crinoid, a marine animal that lived hundreds of millions of years ago. Crinoids, also known as "sea lilies," are related to starfish and sea urchins and first appeared around 300 million years before the dinosaurs.
These animals often possess a long, flexible stem made of stacked, disc-like segments called columnals. In some species, these columnals are arranged in a way that, when fossilized as an internal mold, creates a distinctive screw-like pattern. This phenomenon is well-documented, with similar "screwstones" found in locations like Derbyshire, England. Rock formations in the Marzong Mountain region date back to the Paleozoic era, placing the object's age at roughly 300 million years old—the exact time when crinoids were abundant. The metallic look is likely the result of mineralization during the fossilization process, where minerals replace the original organic material.
While the story of an ancient, manufactured screw is intriguing, the evidence aligns with a natural, albeit unusual, fossil. The Lanzhou Stone is not proof of ancient astronauts and a perfectly preserved piece of Paleozoic sea life.
💡Fun Facts
Crinoids are not plants but animals, belonging to the phylum Echinodermata along with starfish and sea urchins.
Though most abundant in the Paleozoic era, around 600 species of crinoids still exist today, typically in deep ocean waters.
The individual circular plates that make up a crinoid's stem are common fossils known as columnals.
Crinoid fossils have inspired folklore in various cultures; in parts of England, their star-shaped columnals were called "fairy money."