An image of a girl who appears to have three legs has left the internet in a state of confusion.
The snap, which shows a young girl kneeling on a red blanket, is proving so difficult to decipher it has apparently taken one internet user 'two years' to work out.
So does she really have an extra limb - or is this just another clever optical illusion?
The picture has been baffling internet users for some time, but recently resurfaced after it was shared byImgur user AMassiveTRexHoldingaBaby.
They wrote: "Legit had to stare at this pic for a full minute before my brain told me what was going on."
It racked up thousands of views and comments, with one person confessing the conundrum was "hurting his brain".
On closer inspection, the girl appears to be holding a brown vase - but its shape and colour makes it deceptively tricky to distinguish from her legs.
Frustrated viewers confessed they were "still trying to figure it out" after several attempts, with one admitting: "I finally get it. After two years I literally JUST got it."
Imgur user Traso commented: "After you see if you can't see it wrong again.'"
Over Christmas, a seemingly simple picture of six women in a bar left the internet equally baffled.
The snap, posted by Reddit user jr0d7771, shows the friends sitting side-by-side on a sofa, appears to have something amiss - but this only becomes clear on closer inspection.
If you look closely, you will see there are only five pairs of legs for the six women - meaning that the third woman from the left appears to be missing two limbs.
Reddit users were desperate to solve the problem and spent hours squabbling over the correct answer.
Kacie1989 suggested: "I actually think the first girl has [her] legs draped OVER the second girl's legs."
Others were confused by the girl on the far right, whose left leg appeared to be abnormally long.
However the most plausible explanation came from Canadian_Ireland, who wrote: :The second girl's legs are behind the first girl's legs."
This would suggest that the girl with the "missing" legs is actually sitting at a slight angle, with her legs appearing to belong to the friend on her right.
In October, seemingly mundane photo of three women sitting on a park bench was the latest snap to leave internet users scratching their heads.
At first glance the photo appears to show the trio pausing for a sit down during a sunny stroll.
But there appears to be no seat on the bench and the women are hovering mid air.
The most likely explanation is that the bench features smaller pull-out seats.
A photo of a bed with a part of the duvet circled in red went viral last year - with many people failing to spot that the picture is actually a clever optical illusion.
Within the red ring there is a section of a white duvet covered in a black floral pattern, as well as part of the carpet.
However, people who spotted the image - which was shared on Reddit - struggled to work out what the circle signifies.
The image was posted by Imgur user Idon'tevenknowwhat'sgoingon, and received more than 63,500 views in just 24 hours.
Brainteasers like these are becoming increasingly popular online. At first glance the below picture looks like a regular selfie of a woman striking a seductive pose on her bed.
However, if you look closer you will see that something is not quite right with the black and white image.
The shot has been driving the web to distraction ever since it went viral, with puzzlers unable to figure out the oddity.
The image recently resurfaced on Facebook after it first originated in 2003, when it was posted by Deviantart user Missmiserystock. It was titled 'Look carefully'.
Eagle-eyed viewers spotted that the woman actually has six fingers instead of five. The subtle abnormality is likely to be a clever trick of Photoshop, designed to confuse.
Commenting below the snap, one internet user, Bogina, wrote: "Hahaha thats insane it took me a while to catch it good job!" [sic]
But are your eyes sharp enough to solve this brain teaser driving the web crazy?
It is just the latest in a series of brain teasing images baffling the internet.
An image of a floral carpet, uploaded by Jeya May Cruz from Pasig, the Philippines, was shared nearly 16,000 times and reached 120,000 reactions.
Why? Because the photograph contains a camouflaged mobile phone that is devilishly hard to spot.
If you are struggling, the phone has a floral pattern which does not quite match the carpet.
Still confused? The device is just beside the right side table leg at the top of the photo.
It may seem a simple find, but it has left thousands bewildered. Jeya captioned her image: "Since I can't sleep, let's play a game. Look for the cellphone."
Sometimes the easiest-sounding brain teasers are the most difficult ones. And another puzzle to recently sweep the web certainly plays by those rules.
Created by a PlayBuzz user, this colour photo depicts a grey car seat with a mysterious object hidden on it for you to find.
At first, the secret object is impossible to find.
However, after a more detailed search you can spot a grey iPad lying flat on the back on the seat.
The tablet is well-camouflaged because it's the same colour as the seat, with similar markings.