Near the town of Zavidovici, the huge sphere - the largest of a group of such objects - protrudes partially from the ground. According to the archaeologist Sam Semir Osmanagich, who discovered the stone in March, it may have a very high iron content and weigh over 30 tons.
"It could be the largest stone ball in the world," Osmanagich tells a group that has gathered at the object in the Bosnian forest, as can be seen in the following video.
Osmanagich, sometimes referred to as the "Bosnian Indiana Jones" for his worldwide travels, has spent 15 years researching what he calls the "prehistoric stone ball phenomenon".
In a blog written last month for his Archaeological Park: Bosnian Pyramid of the Sun Foundation, Osmanagich suggests that the Bosnian ball could be the largest man-made stone sphere in Europe. He says many others around the world could point to long-lost "advanced civilizations from the distant past" and we have no written record of them.