Decurtins' patterns weren't formed by cracks in the earth, but by molecules: they were mosaic-like tilings of molecules in sheets just one molecule thick. These 2D materials can have peculiar and practical properties that depend on how their molecular building blocks are arranged. For example, it's possible to arrange molecules into 2D patterns that use electrons as computational bits or to store data. Patterns with gaps can act as membranes. And patterns that contain metal ions can be powerful catalysts.