Weird sand 'chess pieces' dot Lake Michigan shore. Here's how they formed.

Bizarre sandy sculptures rising from the beach by Lake Michigan caught the eyes of at least two photographers in early January, who posted their images of the nature-made marvels online.

But what are these sandy statues and how on earth did they come to be?

Their construction depends on several factors, including sand-to-water content and wind conditions, said Daniel Bonn, a physicist and head of the van der Waals-Zeeman Institute at the University of Amsterdam.

Related: Photos of the mysterious sand dune shapes 

The pillars, sometimes called hoodoos, were different heights, anywhere from 3 to 20 inches (7.6 to 51 centimeters) tall, said Terri Abbott, a nature photographer who lives in northern Indiana. Abbott was visiting Tiscornia Park in St. Joseph, Michigan, on Jan. 8, when she noticed the stunning shapes on the snowy beach. 

"Laying on the ground and shooting through these sculptures made it seem like a different planet," Abbott told Live Science in a Facebook message. "They were frozen and hard to the touch. The intricate and ever-so-sharp edges made them each amazing in their own way."

Abbott had never seen sculptures like this before. "I could not believe how perfectly chiseled they were," she added.

Michigan's freezing winter temperatures helped set the stage for the formation of the weird, chess-like pieces, according to Bonn, who was the senior researcher on "How to construct the perfect sandcastle," a study published in the journal Scientific Reports in 2012.

"Roughly, I think that there are liquid patches in the sand that freeze when it gets cold," Bonn told Live Science in an email. The coast is a windy place, he noted. When the sand-laden wind blows into these frozen patches, two seemingly opposing actions happen: In one, some of the sand grains may attach to the frozen patch, making it grow, he said. "This then forms a roughly cylindrical consolidated sandcastle-like structure," Bonn said.

In another, the wind and the sand it carries can erode the sand pillars, taking sand away, which "leads to the rings and the asymmetric shape of the cylinder," Bonn said.

Some of the sand eroded from these pillars ends up elsewhere on the beach. In some photos, "you see that there are point-like structures downwind that result from the sandblasting of the cylinder," he said.

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Joshua Nowicki, a photographer based in southwest Michigan, happened upon the same sand pillars at Tiscornia Park on Jan. 7 and 8. Nowicki, who has seen similar sand structures before, noted that though rare, these pillars can occur at any time of the year, "if there is wet sand and sustained high winds for several days." In most cases, "they only get bigger than a couple of inches tall when the sand is frozen (from rain, melted snow, spray from crashing waves)," Nowicki told Live Science in an email.

The sand sculptures he saw this year "are some of the tallest ones that I have ever photographed, the largest being about 15 inches [38 cm] tall and a couple of inches in diameter," Nowicki noted. "Along the beach, there were at least six groups with thirty or more of the sand structures in a group with one group having quite a few more."

Most pillars don't last long. Usually, within a few days "the wind completely erodes them or knocks them down; if the temperature goes up above freezing, they crumble; and often in the winter they soon get covered by drifting snow," Nowicki said.

The Tiscornia Park pillars crumbled earlier this week when temperatures started to warm, Nowicki said. "The fact that they only exist for a short time makes them very special," he said. "You have to be there at just the right time to see them when the shape is still well defined."

Originally published on Live Science.