Many archaeologists plan explorations of the forest in an effort to understand more about these ecosystems and the history around them. And that's exactly what Bosnian archaeologist Sam Osmanagich did in 2016. He made his way to the Podubravlje Forest in his home country, hoping for some buried treasure, when he stumbled across the most unusual object. It was half-buried in the ground, but he could see that it was in the shape of a sphere.
It was 1.5 meters in diameter and weighed a whopping 30 tons, and after testing, he discovered that it was actually made from volcanic rock. But the answers ended there. It still remains a mystery today.