The puzzle has no natural edge
A tessellation is a covering of a surface with shapes that meet without gaps or overlaps. When the pattern repeats, the same arrangement can be copied again and again, so any edge in a printed puzzle is only the edge of the page—not a place where the pattern must stop.
That changes what “solving” means. In an ordinary jigsaw, a piece with a straight outer edge helps identify the puzzle’s perimeter. In an endless tiling, every exposed side is instead a clue to what could fit next. A shape that looks like a corner in a cropped image may simply continue beyond the crop.
The repeating rule does the work
Many repeating tessellations can be extended by translating a small group of tiles—sliding that unit without turning it. The tile edges constrain their neighbors, and those neighbors preserve the same pattern as it spreads. Once the repeating arrangement is recognized, the puzzle’s continuation follows from the rule rather than from finding a final piece.
A finite display can still have a frame or a selected set of pieces, but those are imposed by the puzzle maker. The tiling itself supplies no last row, corner, or outermost piece. Its apparent border is just where someone chose to stop showing it.
