Yonaguni Monument
Yonaguni, Okinawa, Japan
Underwater structure / Alleged sunken pyramid. Height: 25 m. Date: Natural geological formation: sandstones and mudstones of the Early Miocene (about 20 million years old).
Natural rock formation. Discovered in 1986 by Kihachiro Aratake. Kimura believes it is artificial; geologists such as Schoch consider it probably natural; Japan's Agency for Cultural Affairs and the Okinawa Prefecture do not recognize it as a cultural property.