Even astrophysicist Neil deGrasse Tyson has 'no idea' what the large metal ball that washed up on a Japanese beach really is

• Even Neil deGrasse Tyson doesn't have an explanation for the mysterious ball that washed up in Japan.
• When asked about the ball, the astrophysicist told CNN's Don Lemon he has "no idea" what it is.

A large metal ball that washed up on a beach in Japan has stumped everyone, including celebrity astrophysicist Neil deGrasse Tyson.

In an interview on Thursday, CNN's Don Lemon asked Tyson what the metal ball was.

"I have no idea," Tyson replied in an exasperated tone, causing Lemon to burst into laughter.

Tyson, who is known for his book "The Pluto Files," then said: "Why does everyone have to know everything at all times?"

Lemon then jokingly asked what was the point of having Tyson on the show if he did not know what the ball was.

"You say I don't know about a lot of stuff, Mr Astrophysicist," Lemon quipped.

"Because that's what discovery is," Tyson shot back. "Discovery is what you're doing when you don't know what you're doing."

The mysterious beige sphere, which is about 5 feet in diameter, washed up on Enshuhama Beach in the coastal city of Hamamatsu, state broadcaster NHK reported Tuesday.

It was reported to the police on February 18, but had been sitting in the sand for more than a month, a local told the outlet. An X-ray was performed on it by a bomb squad, and authorities established that it is not explosive, NHK reported.

The appearance started a frenzy on Twitter, with people wildly speculating what it could be. News of the ball came right after another mysterious object —a spy balloon —made headlines recently.

Some said that it's one of the orbs from a popular manga series "Dragon Ball," while others said it's a reptile egg that will hatch to reveal Godzilla, a gigantic fictional reptile monster popularized by a movie franchise of the same name.

But according to Tyson, it's probably not what people are imagining it to be. He said it could probably be a hoax that someone put in the ocean which had washed up.

"People's imaginations just run wild. It's fun, that makes great fiction, but usually it's something less interesting than you imagine," he said.

But out of caution, Tyson advised people to not "poke it unless you're ready."

The metal ball was removed from the beach earlier this week, the BBC confirmed in a report on Thursday. Local officials in the city told the BBC that the ball would be stored for a period of time before being disposed of.

Tyson did not immediately respond to Insider's request for further comment.