The 3-Billion-Year-Old Klerksdorp Spheres Of Ottosdal

In the small town of Ottosdal in South Africa, miners working in pyrophyllite mines have been digging up mysterious metal spheres known as Klerksdorp Spheres. Some of these dark reddish brown spheres have three parallel grooves running around the equator.
The most striking examples have the uncanny appearance of being something manufactured but these metallic objects have been dated to 3 billion years old, a time when the Earth was too young to host intelligent life capable of creating these spheres. Klerksdorp Spheres, however, aren't out-of-place. Neither they are mysterious.