How can a two-piece puzzle be so hard to solve? Well, leave it to Finnish mastermind Vesa Timonen to stump the world's brightest minds with a geometric challenge that requires thinking of mirror-like clarity. You'll be provided with two similar but subtly different wooden pieces. The goal is to arrange the pieces flat on the table to create a shape with a line of symmetry. That means any shape in which you can draw a line down the middle to create two identical halves—each one a perfect reflection of the other. In fact, if you think you've found the solution (good luck!), you can check your work with a small pocket mirror. This is the kind of puzzle that rewards determination with a shining "Aha!" moment.