Comment: Those are

(See in situ)

Those are

eddies which uses centrifugal force to form the circles. Nothing "mysterious" here. In some places during winter, it gets so cold that the pond or stream actually freezes and creates a moving ice circle. Nature is pretty neat.

“When a well-packaged web of lies has been sold gradually to the masses over generations, the truth will seem utterly preposterous and its speaker a raving lunatic.” – Dresden James