New York (CNN) -- The appearance of mysterious giant circles on an ice-covered pond has some upstate New York residents wondering if they've been visited by beings from another realm.
During an unseasonable spring snow storm last Friday, Peggy Gervase of Eden was stunned to see the strange pattern that had formed on the pond she built 10 years ago behind her home. The large circles resembled a black and white Twister game.
Gervase posted a photograph of the pond on Facebook, with a link to CNN affiliate WGRZ's Facebook page, and it received hundreds of comments speculating about what caused the phenomenon.
"People were suggesting all kinds of crazy stuff," Gervase told CNN. "There was everything from ducks swimming in circles to bodies burning to Bigfoot." She got a laugh out of one explanation in particular -- flatulent fish. And the most bizarre of all -- could there be aliens roaming around this quaint town south of Buffalo?
It's likely a more mundane explanation, one expert says.
"There are lots of processes in nature that involve water and convection -- sometimes salt and fresh water, sometimes cold and warm water, sometimes a bit of both. The oceans do this at a range of scales, and it wouldn't surprise me if this is another one of those phenomena where water convects because of a subtle change in temperature," said Timothy Creyts, a glaciologist at the Lamont-Doherty Earth Observatory of Columbia University.
Freeze and thaw cycles common at this time of year cause warm water to rise from the bottom of the pond, disrupting ice formation because of the water's temperature and motion.
"It isn't really a phenomenon. Pond circles are Mother Nature's artwork," Gervase said. "But it took just one photo for people to go wild and then it had a life of its own."
Some scientists are glad the photo has caused such a commotion.
"Everyone who saw that photo and thought, 'I wonder how that happened?' was doing what scientists do every day," said Andrew Juhl, an associate professor at the Lamont-Doherty Earth Observatory. "It's great that people pay attention to these kinds of events and use them to exercise their curiosity about the world around them."