whatA layer of mud dries on the page. It shrinks, it cannot slide, so it cracks: one crack at a time, each new crack running until it meets an older one and stopping there in a T, until the sheet is a mosaic of closed polygons. The slider is the layer's thickness and sets how big the polygons come out. Click to re-wet a patch and it cracks again, differently.

whyDried mud, old paint, glaze on a pot, basalt columns, the polygons of a permafrost plain: the same pattern at every scale, and nobody draws it. It comes from a material that wants to shrink and a ground that will not let it. The piece shows why the junctions are T's and not Y's, which is the fingerprint of cracks that happen one after another rather than all at once.

howThe layer is a lattice of springs, every node glued to the ground by a weaker spring. As the layer dries, every spring's rest length shrinks, so strain builds evenly, and drying pauses whenever any bond is past its own slightly random breaking threshold: the most over-strained bond snaps, one at an instant. A break lets the material beside it relax toward its anchor, which relieves the strain along the crack and concentrates it at the crack's tip, so the crack runs, and it stops where an older crack has already relaxed the ground, at a right angle: a T. Thicker mud carries strain further before the ground pins it, so its polygons come out larger. Cracks are drawn as the seam between the two sides, wider where they have opened more. The readout counts cells and junctions; when the layer is dry it holds, then rain re-wets it all.