Mysterious balls of ice up to seven inches in diameter have washed up on the shore of the Gulf of Finland in north-western Russia. So far, nobody has been able to pinpoint the exact reason behind the phenomenon.

Strangely uniform in size, the spheres were noticed a couple of days ago by passersby who were quick to make videos (above) and click pictures (below). The video above is captioned “Baltic soup with meatballs”, which sort of sums it up quite effectively. On Instagram, someone observed that people in the area must have had a massive snowball fight.

Ilya Leukhin, an ecologist, told local media that this could be the result of oil spills in the water, but she wasn’t the only one trying to understand the phenomenon. Conspiracy theorists on Instagram immediately rose to the occasion. One person wrote, “This is definitely a Communist plot” while another suggested, “Putin might be controlling weather in order to influence the US vote.” Some even raised the possibility that the ice balls are “whale caviar”, conveniently forgetting that whales are mammals.

An assistant professor at St Petersburg’s Russian State Hydrometeorological University, though, may have the best explanation. She said, “As it freezes, seawater passes through three phases. The first is called slush, a fine-granular ice floating on the surface of the water. If the sea is calm, the slush turns into a continuous sheet of ice. If there are waves, it is crushed into so-called pancake ice. If the waves are strong, the slush forms clumps, and what results are these ice ball-like formations.”