Only those with 'expert' eyesight can spot tennis ball hiding in sea of leaves

One of the things you can do to keep your mind active, potentially reducing the risk of dementia, improving concentration, and boosting memory - is attempting brain teasers. These puzzles have been shown to boost productivity, alleviate stress and slow down cognitive decline.

And one particular has been keeping people busy, as apparently only those who are 'experts' at solving these kind of can complete it. One person shared a picture of a pile of leaves on FindTheSniper forum, where people challenge others to find things in images.

They explained that their dog's tennis ball had gone flying into the neighbour's garden - and as there were so many autumn leaves on the ground, it took them "a good five minutes" rummaging through the leaves to find it. The forum user challenged others to try to find the ball in the image, and said it was an "expert level" task.

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It turns out they were right, as many people struggled to find the ball. In the image, the whole ground is covered in similarly-coloured autumn leaves - completely camouflaging the ball.

"Honestly, I'd have bought him a new tennis ball," said one person who failed to find it. Another added: "This was goodun." "At first I was like 'so easy it's right there' but I look and it's a leaf," said a third.

But luckily, some clever optical illusion solvers were able to find it. So take this as your spoiler warning. Take your time and try to find the ball in the image before scrolling down to find its location.

So where is the ball? One social media user shared: "Base of the tree, it's green." Another explained: "2/3rds of the way up. Left side." And a third commented: "That one was hard," and shared a zoomed-in image where they showed exactly where the sneaky ball was hiding.

Ready to test your brain further? Why not try something completely different? The Chase's Darragh Ennis has challenged , which he says is so hard hardly anyone can get all five questions correctly. If isn't your thing, maybe is? Or maybe you can answer this ?