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I found this unusually sphere-shaped stone on a hike. It's about the size of a large gumball.
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What really got me curious, is that a few miles away, I found a second one (the size of large grape) with very similar traits.
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The outer shells are both very rough, like a skateboard top. The cut sides are very smooth and dark.
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The similarities indicate more of a type of formation, and not just a fluke. Anybody have any clue?