In the wetlands of the Paraná Delta, just north of Buenos Aires, there is a curious island known as El Ojo.
What's strange about it? To start with, it floats. It's also a near-perfect circle that sits inside a lake, which itself is circular. Stranger still, El Ojo appears to rotate and shift its position over time.
From the air, this fusion of characteristics makes the island look like an eye – hence its name, El Ojo, which translates into English as 'The Eye'.
It's not known exactly when the unusual feature first formed, but Google Earth captured images of the island in 2003. Then, in 2016, Argentinian filmmaker Sergio Neuspiller drew further attention to El Ojo after spotting it from the air while researching the area for a project.
In an article published in the newspaper El Observador in 2016, Neuspiller says that local residents already knew about the island before he stumbled upon it, with some of them believing that it's the home of an ancient deity.
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El Ojo: what makes it spin?
The island is composed mainly of matted grass, rushes and decomposed plant matter, supported by buoyant layers of other organic material, which helps it float on the water’s surface.
Scientists think that El Ojo – measuring roughly 120 metres in diameter – sits on a current that circles the lake, causing it to rotate clockwise.
As the island spins, it erodes the vegetated banks around it. And it's this that has caused both the island and the lake to become almost perfectly circular.
Do any animals live on El Ojo?
Limited studies of El Ojo make it difficult to know exactly which animals live on the island, but given its size and the habitat around it, it's likely there are some.
Wildlife typical of the Paraná Delta includes river otter, broad-snouted caiman, capybara and marsh deer.
The waters around the island are rich with fish and amphibians, and insects such as dragonflies and damselflies make a home in the marshland vegetation.
Main image: wetlands. Credit: Getty
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