In Racetrack Playa, a Lake in California there are a collection of stones weighing over 45 kilo that clearly, mysteriously move.
When they move, they leave long trails behind and for many years peoples have guessed that hurricane force winds, sliding sheets of ice and of course aliens.
In a paper published in Plos One, two brothers Richard Norris and James Norris worte an article that they caught rocks in the act. They mentioned that "We were sitting on a mountainside and admiring the view when a light wind kicked up and the ice started cracking,Suddenly, the whole process unfolded before our eyes."
Geologists have been studying the sailing stones since 1948, but despite years of research, no one could conclusively say how the rocks moved. That was partly due to the fact that they moved very rarely.