Nishida Jun was a conceptual potter who worked to push the limits of ceramic art. His most celebrated creations were giant balls, filled with equal parts of porcelain and glaze, that he fired at high temperatures until they fused into large masses; he then broke them open and displayed the fragments. This piece from one such experiment is like a geode turned inside out: the exterior (composed of glaze) is crystalline, while the interior (porcelain) is rocky and coarse.