300-Million-Year-Old Metallic Spheres Discovered All Over Earth

I think these large rounded and smooth boulders were caught up in a rapid hydro cycle unimpeded by land masses during a worldwide cataclysmic flood.

The currents so strong they rounded boulders into giant rollie pollies and thats why you will find them having been lodged after the waters finally abated into now hardened sedimentary rock layers and even half sticking out as the softer layers around them erode away.