I thought this was pretty crazy. First you cannot see it and once you do - you cannot unsee it. It took me at least few minutes.
Lots of people manage to see it on their own and some dont, but as soon as you tell them what they are looking at they see it immediately.
I thought this was nice illustration of "3rd man effect" - how our brain does not see things that we dont know anything about. Incredible!
Please do not reveal it if you see it immediately :)
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