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 would n'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 is n'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 . ''
The circles appeared after a storm last week , " Gervase said . Scientists believe warm water from the bottom of the lake is likely the cause . Some believe that birds , fish or aliens were responsible .