People in some parts of England were left scratching their heads as they looked to the skies this week.
Residents in North East Lincolnshire couldn't quite believe what they were seeing when a peculiarly shaped cloud loomed above them yesterday afternoon (24 February).
A number of people took to social media to share photos of the fluffy white mushroom, which lingered in the sky, wondering what the hell it was.
According to reports, the enormous cloud could be seen right across the region, with people branding it 'eerie'.
One of those who spotted it was Joy Bell, from Grimsby.
She told the Grimsby Telegraph: "I was just going to pick my daughter up from school - because I have to go into Cleethorpes to pick her up - but what surprised me was, I just looked in the sky and it looked like an atomic bomb had gone off. It was weird. When I first saw it I was thinking, 'What on Earth is that?!'
"The sky was completely blue and all nice and clear, and it's like all the clouds had formed this circle thing.
"It was really big. I showed the picture to my friend and said, 'Have you seen this?' and she said perhaps there was a fire somewhere.
"And I said it couldn't be a fire because there was no smoke. I said, 'It's definitely a cloud', and when I took the photograph and zoomed in, I could see that it was all mist at the bottom and then cloud at the top.
"It certainly made the school run an interesting one as I whipped out my camera and managed to get a good picture."
And she wasn't alone.
Sharing their own snap to Twitter, one spooked onlooker wrote: "Ominous looking cloud over #Cleethorpes this afternoon on today of all days."
Commenting on a Facebook thread of photos, another said: "I hope that's not an omen."
But it wasn't anything sinister at all.
According to one user, it appeared to be an anvil cloud, otherwise known as a Cumulonimbus cloud.
On the Met Office's website, experts describe these as: "More commonly known as thunderclouds, cumulonimbus is the only cloud type that can produce hail, thunder and lightning.
"The base of the cloud is often flat, with a very dark wall-like feature hanging underneath, and may only lie a few hundred feet above the Earth's surface."
So it's nothing to worry about, just another quirk of Mother Nature.