Japan removes mystery metal ball washed up on beach in Hamamatsu

Many took to social media to correctly identify the puzzling object

The iron ball is seen on a beach in Hamamatsu, Japan, on Wednesday. Reuters

A large yellow iron ball that washed up on a beach in Japan's Hamamatsu city has been removed after its arrival prompted online speculation that it was anything from a bomb to a UFO.

The huge ball, referred to as a "Godzilla egg" by some, perplexed Japanese authorities, police and a bomb squad who inspected it on Wednesday soon after it appeared on the shore.

X-ray exams confirmed the object was not an explosive device.

But many took to social media soon after to point out that the object was nothing more sinister than an ocean ball buoy.

What was Japan's mystery ball?

Hamamatsu's local civil engineering office said it considers the object to be a "foreign-made buoy".

"I think everyone in Hamamatsu city was worried and curious about what it was about, but I'm relieved that the work is over," a local official told Japanese media.

Prof Mark Inall, an oceanographer at the Scottish Association for Marine Science, told the BBC he knew what it was "instantly".

"It's very recognisable. We use (them) to keep instruments floating in the ocean," he said.

Professor Inall said ball buoys often wash up on the coast of Scotland.

He said he was surprised that the metal sphere was not identified more quickly but said the general public would not necessarily have known what it was.

"It could be confused for a World War Two mine, but those would have spikes sticking out of them," he said.

The buoys can float in the ocean for decades, becoming rusty and losing their markings when they wash ashore, he said.

The discovery of the ball comes amid heightened concern in Japan over North Korea's recent missile activity.

On Saturday, an intercontinental ballistic missile landed in Japan's territorial waters.

On Monday, North Korea fired two ballistic missiles into the Sea of Japan after the US held joint exercises with East Asian allies.

Japan has also held security meetings with China in Tokyo to express concern over the issue of spy balloons said to belong to China.

"Given the recent events, I could understand there's an interest in an unidentified floating object," Prof Inall said.