12 Incredible Things On Earth You Probably Didn't Know Existed.

This article is based on "These 12 Crazy Things Were Found On Earth, and Some Of Them Still Can't Be Explained" and "10 Authentic Historical Artifacts No One Can Explain". If you're interested in reading more, check out the links at the bottom of the article. Sources for individual points are hyperlinked numbers.

When we think of unsolved mysteries we tend to think of crop circles or Jack the Ripper, but there's plenty of unsolved mysteries from history and archaeology that rarely make the front page. All of the following artifacts and archaeological sites were found on Earth and while there have been many hypothesis, we can't explain their origins or purpose.

1. The Longyou Grotto Caves

Located in Zhejiang, China the Longyou caves are 36 underground grottos measuring 30,000 square miles. Dating back to at least the Qin Dynasty in 250BCE, the grottos were found submerged in water but perfectly preserved. There's no record of their construction or mention of them in documentation from that time period. Their purpose and usage are unknown. While its has been hypothesized that they were catacombs there are no spaces dedicated for burial and there's no signs of anyone ever living there.

2. The Voynich Manuscript

Named for Wilfrid Voynich, the man who discovered this book in Italy, the Voynich Manuscript has stumped scholars since the early 1900s. The manuscript dates back to 15th century Europe but the language doesn't match anything from the time period. A variety of botanical and astronomical drawings suggest that it may have been used as a pharmaceutical guide but despite numerous attempts it has never been translated.

3. Stone Spheres in Costa Rica

In 1940 plantation workers in Diquis Delta, Costa Rica discovered over 300 spheres made up of granodiorite ranging in size from 3cm to 3m. The stones were created by moving boulders to a quarry where they were hammered into perfect spheres before being moved another 50 miles away to their current location. When they were discovered the stones were organized in lines or geometric patterns but they were unfortunately moved for construction purposes so the rationale behind their location and purpose are lost. Their significance remains a mystery.

4. The Gate of the Sun

The archaeological site of Tiahuanaco, Bolivia used to be a sea port before water levels receded leaving the area barren and desolate. The Gate of the Sun is one of a few ruins still standing in the area, though it had to be returned to its original position after it was originally discovered fallen over. The figures engraved on the gate may be astronomical and many believe it was used as a calendar. The true purpose of the entire structure is unknown however, though one extreme theory guesses that it may have been used as a metaphoric gateway to heaven.

5. Yonaguni Monument

Off the coast of Yunaguni, Japan is an underwater rock formation originally thought to be naturally forming. However closer inspection reveals depictions and cut markings on the stone meaning it was man-made from at least 5,000 years ago. It is unknown what civilization built the formation, what the entire formation looked like, or the purpose of the building. Based on documentation from the time period in Japan it is postulated that the structure sank in a tsunami.

6. Stone Age Tunnels

A series of underground tunnels dating back 12,000 years have recently been uncovered all over Europe from UK to Turkey. The tunnels are small enough for a person to crawl through with very tiny rooms potentially for sleeping or bathing. The tunnels have been found across the continent though they are not all connected. This discovery reveals that the Stone Age humans were less rudimentary in their architecture than originally thought. That being said the goal of such an elaborate tunnel system is unclear. They were potentially used to hide during war or to travel safely but the small size of the tunnel suggests these are unlikely.

7. Gobekli Tepe

Temple ruins from 9000BCE was uncovered in Urfa, Turkey in the 1960s and may be the world's first temple. A widely accepted theory about ancient civilizations is that settlements were established first and once people had more time to explore other aspects of their culture they would build ritual or recreational areas. This discovery flips that theory on it's head, as the nearest settlement is dated after the temple ruins, suggesting that the settlers built a settlement for the purpose of being closer to the building they were constructing. Though this temple was constructed 6000 years before the invention of writing there are still symbols, though not translatable, meaning we have no idea who the temple honors.

8. Rongorongo

Twenty-six wooden tablets and other small artifacts were found on Easter Island off the coast of South America with undecipherable writing on them. It is speculated that the tablets date back to the 13th century but this is widely disputed. The Rongorongo language is composed of shapes and geometric forms and thought to be read left-to-right. Unfortunately due to limited number of examples and no code to decipher the language (and what it is trying to convey) remains a mystery. Some people believe it is just decoration.

9. Roman dodecahedron

A dodecahedron is a 3-dimensional shape with twelve flat faces, each face in the shape of a pentagon. These palm-sized dodecahedrons were found scattered across what used to be the Roman empire but there is no record of them from that time period. Their non-obvious usage has led people to conclude that they could be measuring tools, candle holders, or even parts of a game, but their true origins are unknown.

10. Fulachtai Fiadh

Also known as a burnt mound, Fulacht fiadh from the Bronze Age are found across Ireland, usually near a water source. The purpose of these shallow pools of water is unknown, but the given name gives us some hints. "Fulacht" is an Irish word meaning an open-air cooking place, suggesting that perhaps the pools were filled with water and heated stones would make the water boil for cooking meat. However few cooking tools or animal remains have ever been found in proximity to a fiadh. Other suggestions are that they were used as saunas or for bathing with tents pitched overtop of them.

11. Phaistos Disc

The Phaistoc Disc is a 4000-year-old clay disk found in the early 1900s on Crete, an island in Greece. Carbon dating suggests that it is a product of the Minoan civilization. Based on the shape and pattern of the symbols some think its a record of the alphabet but none have been able to identify or translate the language. Beyond that, the disk itself has not been identified beyond the possibility of decoration.

12. Stone labyrinths of Bolshoi Zayatsky Island

On Bolshoi Zayatsky Island in North Russia are many sacred sites and villages dating back to 3000BCE. However there are also many spiral labyrinths comprised of 2 rows of stones, which have since overgrown with vegetation. Labyrinths of this style are not common to this location or era, and beyond Russia are not a common archaeological find. It is assumed that they were used ritualistically but beyond that serve no known purpose.

Source: 1, 2

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