Today’s Wonder of the Day was inspired by Elijah. Elijah Wonders, “How the Stone Spheres of Costa Rica were made?” Thanks for WONDERing with us, Elijah!

Do you have a list of places you want to go one day? Are you a fan of warm waters and beautiful beaches? If so, you may dream of visiting the nations of Central America. Or perhaps you’re one of the lucky people who live there year-round!

Today’s Wonder of the Day is all about an interesting phenomenon nestled deep in one of these nations. What do you think of when you hear the name Costa Rica? Pristine beaches along the Pacific Ocean and the Caribbean Sea may come to mind. You might also picture lush jungles and tropical rainforests. Of course, you might also think of hundreds of huge stone spheres. Wait . . . what?

Yes, you read that right. Costa Rica is also famous for its large collection of almost perfectly round stone balls. To learn more about these stone spheres that dot the landscape of Costa Rica, we must travel back in time to the early 1930s.

At that time, the United Fruit Company was searching for new land for a banana plantation. They found a prime location in the Diquis Valley. This valley is located in western Costa Rica near the Pacific Ocean.

As workers began clearing the dense jungle lands, they found something strange: stone spheres. Some were only a few inches in diameter. Others were huge. The largest spheres measured as much as seven feet in diameter and weighed 16 tons.

Where in the world did these spheres come from? Or did they even come from this world? Locals quickly began speculating, and many myths developed to explain the stone spheres. For example, some believed they were brought to Earth by aliens. Others think they are linked to the lost continent of Atlantis.

The scientific study of the stones began in the late 1930s and early 1940s. To date, about 300 of the stone spheres have been found across Costa Rica. Many of the stones are not perfectly round. However, they are surprisingly smooth. Scientific measurements show that many of them are very close to being perfect spheres. Archeologists believe that the stones were most likely handmade. They think this was done by ancient people indigenous to the Diquis Valley.

Most of the stone spheres were sculpted from granodiorite. This is a very hard rock similar to granite. Scientists believe ancient peoples likely chose large boulders that were already somewhat round. Then, they carefully shaped them using smaller rocks of the same material as tools. They also think that ancient sculptors may have heated portions of the stones and then cooled them rapidly. This would have helped to remove the outer layers of rock.

Many of the stones still contain marks from the tools used to shape them. The smoothness of the surfaces was probably achieved by polishing the finished stones with sand or leather. Scientists haven’t been able to pin down the exact time when they were made. Estimates range from as early as 200 B.C.E. to as late as the 1500s C.E.

The most difficult question to answer is why the stones were made. What was their purpose? No one knows for sure. But a few theories have developed. Some believe they were used as compasses. Others think they align with astronomical phenomena. People also think they were used as grave markers or status symbols, marking the property of ancient leaders. What was the true purpose of these ancient stones? The world may never know.

Standards: CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.4, CCRA.R.10, CCRA.SL.1

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