Media playback is unsupported on your device Media caption The giant ice disc has been slowly spinning

A rare natural phenomenon taking shape in the US state of Maine is mesmerising people around the world.

A giant slow-turning ice disc, measuring approximately 91m (298ft) wide, has formed in the Presumpscot River in the city of Westbrook.

The captivating natural oddity has drawn comparison to an alien spacecraft, a carousel and the Moon.

Researchers believe ice discs spin because of temperature changes in the water, creating a vortex underneath.

The movement chips away the edges, creating its circular shape.

The large rotating disc has served as a raft for ducks and other birds, news reports said.

City of Westbrook authorities were notified of the disc by a local businessman, and used a drone to capture the moonlike ice formation.

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