Scientists have spotted possibly dozens of mysterious craters in Siberia’s remote Yamal Peninsula, a region that gained attention last year after video footage emerged of an enormous hole in the ground that appeared to form out of nowhere. Researchers expect there could be as many as 20 to 30 unexplored craters dotting the peninsula, based on recent satellite data, according to the Siberian Times. Their findings were revealed Monday.

The satellite images exposed the sites of several larger, previously known craters, but also revealed many so-called baby craters -- smaller holes surrounding the larger ones. “I would compare this with mushrooms: When you find one mushroom, be sure there are few more around," Vasily Bogoyavlensky, a scientist with the Russian Academy of Sciences and deputy director of the Oil and Gas Research Institute in Moscow, told the Siberian Times.

Scientists have called for studies to determine the reason for the craters’ sudden appearance. Researchers have previously suggested a link to climate change or gas eruptions. "These objects need to be studied, but it is rather dangerous for the researchers,” Bogoyavlensky said. “We know that there can occur a series of gas emissions over an extended period of time, but we do not know exactly when they might happen.”

The region, known as the “End of the World,” is located in northwest Russia and is mostly covered in permafrost, a layer of soil that stays frozen year-round. In July, reindeer herders traveling along a pasturing route stumbled upon three enormous, cone-shaped craters that looked out of place on the flat, barren landscape. The first hole, the largest of the three, measured 80 meters (260 feet) wide and plunged to an unknown depth. Two other holes were discovered two weeks later, one measuring about 15 meters across and the other about 5 meters.

Theories about the sinkholes’ origins have been widely circulated and ranged from meteorites to being a man-made prank. Scientists, however, have said the holes probably formed because of explosive gas emissions from deep within the earth’s crust. Locals told investigators they had felt tremors in the area around the time the first craters appeared.

“Could it be linked to the global warming? We have to continue our research to answer this question,” Andrey Plekhanov, a senior researcher at the State Scientific Center of Arctic Research, told the Times last year. “Two previous summers -- years 2012 and 2013 -- were relatively hot for Yamal, perhaps this has somehow influenced the formation of the crater.”