This massive rotating ice disk in a Maine river is freaking people out on social media

WESTBROOK, Maine -- A curious formation that's getting attention in Greater Portland is actually a spinning ice disk that is roughly 100 yards wide.

The formation in the Presumpscot River was widely shared on social media and has drawn comparisons to an alien spacecraft, a carousel and the moon.

The oddity drew a crowd that stood mesmerized by the slow-turning disk Tuesday afternoon in Westbrook.

The ice formation is believed to have formed naturally in a part of the river where there's a circular current that creates a whirlpool effect, said Tina Radel, the city's marketing and communications manager.

Locals say they've seen smaller ice disks before, but nothing like this one, Radel said.

Rob Mitchell, who owns a nearby office building, spotted the alien-looking disk Monday morning and immediately notified the city.

Officials say the disk is spinning slowly counter-clockwise, and has served as a big raft for ducks and other birds. "The ducks were rotating on this big Lazy Susan," Mitchell said.