Scientists in Argentina have been left bamboozled by the bizarre formations that appeared over night.
It has been reported there were 15 enormous rings left etched into the landscape at an area locals believe is visited by aliens.
However, footage appears to just show three of the odd circles.
The rings appeared on March 17 in the town of Carmen de Areco near the capital Buenos Aires.
Strangely, each circle appeared to be exactly the same height and width and were said to have appeared one by one while residents slept.
Unlike intricate crop circles in the UK, they were just circles with nothing inside.
Crop circles were exposed in the UK in the 1990s as the work of pranksters using wooden planks, but some alien chasers still believe they are left as signs by aliens or are even the landing marks of a UFO.
Scott C Waring, editor of ufosightingsdaily.com, said: “The circles appear deep and down to the dirt as if burnt by radiation.
“I wish they had used a Geiger counter to measure radiation in the area. This could be a landing place of a UFO that frequently passes by and each time leaves a mark in the shape of the bottom of the craft.”
The incident caused such a stir, the mayor of Carmen de Areco, Marcelo Skanski, spoke to reporters at the scene.
He told them he had asked for experts from the UFO Study Commission of the Argentine Republic to investigate.
Investigators are taking grass samples to be analysed by the Agronomy department of the University of Buenos Aires.
The experts were intrigued by the uniformity and precision of the circles and were not ruling out an alien element.
But sceptics are pointing to it being another elaborate hoax.
Scott Brando, who runs hoax-busting website ufoofinterest.otg, told Express.co.uk: “I read this news but there are three circles, not 15.
“Someone tried to make a joke?
“If you look closely the circles, the outer borders shows several spots outside the circular line, like if someone was dropping or spraying something (maybe bleach) with the back to the centre of the circle.”