The latest brainteaser sweeping the web is bound to make your eyes boggle.
Internet users are well and truly flummoxed after being challenged to spot the letter b among the d's in an increasingly difficult series of levels.
With the lowercase letters looking almost identical to each other, the b is deceptively tricky to spot - and the makers at Playbuzz claim you have to be not only extremely patient but have a high IQ in order to succeed.
For each level, there are three boxes filled with several rows of the letter d, with just one of them containing a rogue b.
But beware, on each level there are more b's than before, making the odd letter out increasingly difficult to spot. And confusingly, not every box contains the same number of characters.
In level one there are just 12 letters in each box, making the task relatively simple. But by the eighth and final level, there are more than 150 characters to choose from.
The puzzle, posted online, has racked up hundreds of likes and comments and left the internet well and truly baffled with one user claiming it had made his eyes "go dizzy" while another admitted it had given him a headache.
But it is just the latest puzzle to baffle the web. Last week, the internet was bamboozled by a festive brainteaser in the form of a fiendish elf hiding in a snow-capped evergreen forest.
Santa's little helper is nestled among the more than 150 firs, proving that elves can be just as good as Santa when it comes to sneaking around at night.
There are a number of confusing elements to the puzzle, like a golden mountain trail that draws your eye away from Santa's little helper, and the tree tops which are the exact same colour as his hat.
With the nation well and truly in the Christmas spirit now that December is upon us, Eco2greetings came up with the eye-boggling brain teaser to remind shoppers that wrapping paper and cards can be recycled over the festive season. So have you spotted him yet?
The elf is located towards the bottom right of the image, cleverly concealed between two firs in a camouflaged green hat.
This is not the first festive puzzle to emerge this year with an eye-boggling Christmas brainteaser doing the rounds earlier this month.
In a group of reindeer users are asked to spot a little red-breasted robin perched on one of their backs. He's sitting snug, staring straight at you while you're trying to figure out exactly where he is.
This latest brainteaser from focus will really test your eyes and see whether you can see the difference between the robin and the reindeer.
The red noses of the reindeers camouflage the robin's red-breast perfectly.
There are a number of confusing elements to the puzzle, such as reindeers with patterned horns, red and yellow scarves and Santa hats which draw your eye away from the robin.
Another winter themed brainteaser shows rows and rows of knitted jumpers, hats and scarves - but hidden between them is a bucket and spade, which internet users are struggling to spot.
The bucket and spade are exactly the same colour as the other items in the image, making them very tricky to find.