There are more and more unearthed artefacts giving a hint that we might not have been alone and our species was not the only intelligent one.
There are some mysterious stone spheres in Costa Rica and archaeologist still cannot explain their origin and how they were made. They were found in the 1930s in the jungle of Costa Rica.
Their age is estimated to be at least about 500 years which gives more headache to finding the answer because there was not any technology which could have made such spheres at that time. However, it seems that the stone spheres have an artificial origin. They are almost perfect geometrical spheres and there are around 300 of them.
Their size is varied between 2 cm to 2 meters, some weights 15 tons. Some of them were made of limestone, sandstone or granite. None of them has decorations or marks. Tools were not found around these objects so we do not know how they were produced. It is possible that they were made but humans but we do not know how.
Nonetheless, somebody created them in a way that would last for an incredibly long time. Do they hide something? What we know for sure is that their presence does not fit the historical context. Some believe they represent planets including the Earth but how is that possible considering the fact that Flat Earth Theory was still popular in the middle ages? A more improved idea suggests that the spheres could have been used for the simulation of the movement of certain planets. Is it possible that an alien civilization taught us about their solar system?
What is certain is that nature cannot produce such spheres. However, according to some theories, they could have come from underground in the form of minerals and were formed into spheres for hundreds of thousands of years but this explanation has never been proved.
According to another theory, the spheres were made by the extinct Diquis culture but it has not been proved either.
There are more mysteries on Earth than we think. If these spheres could speak, they would tell us more about them.