Science can help explain a lot about the natural wonders of the world, but it doesn’t have an answer for everything. Sometimes, experts are left scratching their heads at how certain structures came to be.

In Sioux County, Nebraska, there are tens of thousands of fossilized spirals that, for the longest time, had scientists and historians stumped at how they got there.

They’re known as the “Devil’s Corkscrews,” and the origin behind them is absolutely fascinating…

Science has helped researchers and historians make leaps and bounds when it comes to answering puzzling questions about the origins of certain natural wonders. But, sometimes, the answers aren’t all that clear, and experts are left scratching their heads. In Sioux County, Nebraska, there are tens of thousands of fossilized spirals that have confused experts for years…

The strange shapes were given the nickname the “Devil’s Corkscrews” many years ago because of their shape and mysterious origin. Because there was no plausible explanation for them at the time, people figured it must have been the work of dark forces.

The spirals all vary in size and age. Some can grow up to 15 feet in length, and most of them are around 15 to 30 million years old! They’ve been around Sioux County since the dinosaurs, too. But what exactly caused these bizarre formations?

For the longest time, scientists could not explain how these perfect spirals were formed. People reported finding these odd shapes all over the county. Some theorized they were petrified vines, while others thought they were massive fossilized worms that once lived in the area millions of years before. But the truth is even more fascinating than these theories…

James St. John / Flickr

The spirals were actually made by a prehistoric animal, but not worms like some people thought. The creatures behind the perfectly crafted spirals were ancient beaver-like animals called Palaeocastor.

The burrowing animals lived in the North American Badlands during the late Oligocene period. They would make corkscrew-shaped burrows and tunnels under the ground where they lived and sought protection from predators.

The corkscrew tunnels were always vertical, but the animals also had smaller nesting chambers on the sides that jutted out from the corkscrew tunnels. The entire underground system these animals built was very impressive.

After the animals died out millions of years ago, trees and other vegetation started growing in the area where they made their burrows. The roots of those trees would grow down into the spirals and eventually fossilize into the hardened, swirling shapes.

This is a photo of one of the largest corkscrews found in Nebraska. As you can see, the spiral shape is absolutely perfect, and at the base of the formation is a massive root that extends outwards. This root served as a small nesting chamber for the Palaeocastor.


What a fascinating origin story for these bizarre formations! The animals who created the spirals certainly had a unique way of making their homes. It’s incredible that, even after millions of years, these shapes remained intact.

If you’re interested in checking out the fossils yourself, you can visit Agate Fossil Beds National Monument located on the Niobrara River in northwestern Nebraska.

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