UFO watchers are stumped after mind-blowing footage captured a strange black shape in the skies over America’s third largest city. Aiyana, who asked that her second name be withheld, recorded the clip from the roof of her home in Chicago, Illinois, and is at a loss to explain it. In her video, a long black wishbone shape can be seen hanging in the air, with both its wings ending in some sort of sphere. Aiyana said: “I literally have no idea what it was. There is nothing comparable. “It was a ball of some sort with two long strings or belts hanging from it. The strings had knobs in the middle and bottom. “I felt total confusion and a bit creeped out. “In the video, you can hear my son and I talking about it and trying to figure out what it was. “Neither of us had any idea what we were seeing.” Searching for answers, a friend of Aiyana’s shared the video with UFO watchers online. A few viewers suggested it was some kind of balloon, but nobody could explain how such a thing could float so calmly above the famously “windy city”. One person wrote: “I’ve never seen a balloon just hang still in the open air like that. It should bob, even if just a little. “There must be absolutely zero wind there.” Another called it “bizarre”. They wrote: “I have no explanation. It looks like something hanging from a helicopter, except there is no helicopter. “The shape is too weird for it being a balloon, and I think I can also exclude it being an antenna on top of a building in cloud cover – for this, it is way too clearly defined. “I have no idea!” One viewer chimed in with local knowledge. “A balloon usually has some movement,” they said. “I live in Chicago. Even on a still, calm day, Chicago and the surrounding areas have wind of some sort and would move something in the air.” Another person compared it to a “floating sex swing”. The true nature of the object remains a mystery. Aiyana said she stayed watching it until it disappeared from view. “It seemed to just float slowly south east without any other major movement,” she said. “It covered a few miles in about 20 minutes.” The unexplained sighting is just one of several in the US in recent weeks. Another UFO video, captured in Baltimore, Maryland, attracted a deluge of comments revealing identical sightings in numerous states. Meanwhile, footage from Keokuk, Iowa, left people stumped after it captured something resembling a star suddenly moving in the daytime sky.