Cut this trotting pony into six pieces, rearrange them, and a different horse appears
Sam Loyd's Pony Puzzle gives you a picture of a small pony sliced into six interlocking pieces. Rearranged one way, the pieces show the original pony. Rearranged another, the same six pieces form a completely different horse, with the 'new' animal hiding in the gaps between the parts. Loyd built it after visiting England's ancient Uffington White Horse hill figure.
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The six pieces are cut along curves that do double duty: each line is simultaneously part of the pony's outline in one arrangement and part of the second horse's outline in the other, once the pieces are shifted and some flipped. It's a classic example of Loyd's favorite trick, using ambiguous, shared contours so the same fragments read as two completely different pictures depending on how they're assembled.
— Sam Loyd, The Pony Puzzle — Puzzle, 1870s
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