The Japan Coast Guard announced that the "Godzilla Megamullion"—a massive seafloor formation found during its 2001 continental‑shelf survey—has been added to the International Union of Geological Sciences’ list of 100 Geological Heritage Sites. This recognition highlights the feature as a rare and valuable part of Earth’s geological record.

The dome stretches about 125 km long and 55 km wide, which is roughly ten times larger than a typical megamullion. Because of its extraordinary dimensions, scientists consider it the largest megamullion ever discovered.

A megamullion forms when mantle rocks are exposed on the ocean floor through fault activity linked to seafloor spreading. The Godzilla Megamullion sits on the Philippine Sea plate, southeast of the remote Tokyo‑administered island of Okinotorishima, illustrating this process on a huge scale.

The feature was named after the monster Godzilla because of its enormous size, and it was officially registered under that name in 2021. International research led by Japanese scientists has used the site to reveal important details about mantle structure and the mechanisms of plate formation, underscoring its scientific value.

In short, the Godzilla Megamullion’s record size and unique origin make it a key reference point for global geological research. Its inclusion on the IUGS heritage list confirms its importance for future studies.