Brain teasers can come in the form of puzzles, phrases, riddles and statements, all designed to confuse the brain.
They have a concealed or double meaning, leaving many people scratching their heads.
One riddle is claiming that it can only be solved by “smart people”.
The brain teaser was posted on SilverDoorApartments.com, and comes with the intro: “Think you’re the smartest one in the office?
“Our collection of head-scratching riddles and brain teasers will settle the battle once and for all…”
Brain teaser: This riddle claims only ‘smart people’ can solve it – are YOU clever enough?
The riddle calls on people to try and identify what a cryptic object is.
The brain teaser goes like this: “I don’t have eyes but once I did see.
“Once I had thoughts but now I’m white and empty.
“What am i?”
The brain teaser is sure to leave many people confused, but there is one simple answer.
Brain teasers are designed to confuse the brain and play tricks on you
Possibly taking some time to work out, the unusual answer to the question is a skull.
Skulls are the focal part of a skeleton once being home to eyes, but now being empty.
The riddle forms part of a series of brain teasers on the real estate website, challenging “smart” people to solve them.
Another trick confusing the internet is an optical illusion.
The surprising answer to the riddle is a skull
Some make you question whether you should believe your eyes at all.
Made up of colours, patterns and shapes, a good optical illusion can leave your confused.
They also leave you wondering what the real image actually is, and why your brain is playing tricks on you.
One image has appeared online that does exactly that, asking viewers to decide whether the lines running down it are parallel to each other or not.
Appearing in bright pink and yellow, the colours and lines work together to deceive your eyes, with the pink lines having smaller cross-hatched lines running through them.