From Costa Rica's Great Balls to Death Valley's wandering rocks: The 10 bizarre phenomena that still have scientists baffled

From Costa Rica's Great Balls to Death Valley's wandering rocks: The 10 bizarre phenomena that still have scientists baffled | Mail Online:
"From Costa Rica's Great Balls to Death Valley's wandering rocks: The 10 bizarre phenomena that still have scientists baffled
Great balls of Costa Rica date back to 600AD yet their purpose is unknown
In Serbia and Japan, frogs and other wildlife are said to fall from the sky
Stones slide across the ground under a mysterious force in California.
While no one knows how vast shapes appeared in Peruvian sand"