In 1986, diver Kihachiro Aratake swam along a submerged rock mass off Yonaguni Island, at Japan’s western tip, and found terraces sharp enough to photograph like architecture. Dive boats followed. Marine geologist Masaaki Kimura mapped the formation as anthropogenic or terraformed. Other geologists—Robert M. Schoch among them after 1990s dives—read the same steps as sandstone and mudstone breaking along bedding planes and vertical joints in an earthquake-prone shelf. This Archive file stays contested.