From the NPR blog Krulwich wonders.
What we have here is the EverReady battery of puzzles. It just keeps going and going.
Each of these figures is built from the same 7 elements: two big triangles, two small triangles, one medium size triangle, a rhomboid and a square.
Put together differently, the same pieces would form a square.
All over the world people have created sly, elegant, silly, mathematically curious combinations using only the original 7 elements, no overlaps allowed. The possibilities are dazzling.