A small, uninhabited island off the coast of Japan is no more.

Esanbe Hanakita Kojima was one of Japan’s 158 remote, uninhabited islands that the government named in 2014, the Guardian reported.

However, it’s unclear whether the island even existed when it was named. The last time the Japanese government formally surveyed the island was in 1978, and fishermen would avoid the area because it showed up on maps as an underwater reef. It’s likely that wind and drift ice eroded the island, according to the coast guard.

Recently, Hawaii’s East Island disappeared as well. However, that was a sudden disappearance caused by a hurricane. The Japanese island could have disappeared over the course of decades.

The disappearance of the island could have territorial implications for the country, according to the Japanese news outlet the Asahi Shinbun.

The island was used as a formal territory of Japan, meaning the area nearby was formally Japanese territory. As the islands are located between Japan and Russia, the loss of an island will create a larger gap between the two territories, according to Newsweek. Russia had also named a handful of islands near their mainland to expand its borders.

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Locals had not noticed the island disappearing, and may not have known for a long time if had not been for an author who was hoping to study it. Author Hiroshi Shimizu is writing a book on Japan’s “hidden” islands, and travelled to the area to find them.