Sonic X, the anime series based on the Sonic the Hedgehog video game, was an integral part of many people's childhood. With 78 episodes in total, it saw our favourite blue erinaceinae fight the dastardly Doctor Eggman after accidentally teleporting to Earth.
Each episode featured a recognisable logo showing Sonic himself in profile. But it turns out that people interpreted the design in different ways thanks to an optical illusion that gives Sonic an unintended amusing expression (see our pick of the best optical illusions for more mind benders).
