As you may have noticed, the entire world has been experiencing some bizarre weather, ranging from soaring temperatures in the Arctic and intense El Niño-driven downpours that have one river in Argentina cresting at 46 feet above normal. But if that’s not quite weird enough for you, here’s something even more bizarre phenomenon: a lake in Maine with waves of what appear to be snowballs.

David Allen, a land art and sculpture artist with Stone Point Studio, spotted of the strange tides crashing into the shore of Lake Sebago in Maine and posted a video that has created a sensation on the Internet.

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On the studio’s Facebook page, Allen said that he shot the video from the town beach, on the northwest side of the lake. The area had experienced unseasonably warm weather, followed by a sudden cold snap and a snow and sleet storm, he wrote. Though there wasn’t any surface ice on the lake at the time, the waves were filled with snowballs.

Allen, who fished a couple of the balls out of lake, found that they were slushy, rather than hard ice. He hypothesized that they might have formed from snow that had been caught by a nearby jetty and formed slush on the water surface that was shaped by the wind.

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That explanation would be similar to the process that sometimes forms giant ice balls in Lake Michigan. Chunks of ice break off from large sheets that form on the lake, and the tumble in waves created by strong wind. That rounds and smooths the edges of the chunks, shaping them into roughly spherical frozen boulders. Additional layers of ice accumulate on them, before they wash ashore.

Another strange winter phenomenon is snow rollers, which are hollow tubes of snow that from when there’s a rare combination of light, sticky snow, moderately strong winds, and cold temperatures.