Complex rock formations aren't exactly common in the rain forests of Brazil, so when they pop up, people take notice, even if they don't immediately do something about it.

Such was the case for Lailson Camelo da Silva, a former ranch foreman. Da Silva discovered the site in the 1960s while hunting wild pigs around Calçoene, Brazil, but he stayed away from it until the 1990.

"The place initially felt sacred, like we didn't belong here," da Silva told the New York Times, "but it was impossible to miss it during the deforestation drive of the '90s, when the priority was to burn down trees."

Since then, scholars like Mariana Cabral from Brazil's Federal University of Minas Gerais have excavated the area, finding shards of pots and urns. Cabral has also identified a part of a nearby river where the rocks may have been quarried.

As for the stones themselves, Cabral thinks they served as a type of calendar and astronomical observatory — just like Stonehenge in England. But this site in Brazil existed 1,000 years ago, well before Europeans began to arrive on South American shores. The site may have also been used for rituals associated with solstices.

Of course, the very existence of the rocks raises another question, one da Silva — who now serves as the custodian of the site — has mused on as well: "It makes me wonder: What other secrets about our past are still hidden in Brazil's jungles?"

Good question. Perhaps a young man is hunting in the rain forest now, about to discover another lost secret.

The Amazon has its own Stonehenge?
Located in Calçoene, Brazil, this mysterious rock structure, known as Amazon's Stonehenge, has scientists re-thinking ancient Amazonian society.