WHEN the mystery object at the bottom of the Baltic Sea was first spotted in 2011, it baffled experts and excited alien hunters. They still don’t know what it is.

Dubbed the “Baltic Sea Anomaly”, the structure looks like the Millenium Falcon from Star Wars.

It was discovered five years ago by Swedish treasure hunters, Ocean X team, led by Peter Lindberg, its captain, and his co-researcher Dennis Asberg, The Sun reports.

They used a side-scan sonar and found something strange 91 metres below the surface of the water.

It was reported that the divers exploring the anomaly said their equipment stopped working as they approached it.

“Anything electric out there, and the satellite phone as well, stopped working when we were above the object,” professional diver Stefan Hogerborn, part of the Ocean X team, said.

“And then when we got away about 200 metres, it turned on again, and when we got back over the object it didn’t work.”

The 61-metre-wide and eight-metre-tall circular object hit the headlines, with many speculating the anomaly could be a giant mushroom, a sunken Russian ship or an alien spaceship.

A sample recovered by divers was given to geologist Steve Weiner who ruled out the possibility of it being a natural geological formation.

After examining fragments, he claimed that the materials were “metals which nature could not reproduce itself”.

Some experts think it’s a Nazi anti-submarine device or a battleship gun turret.

Other observers believe it is a UFO called the “Roswell of the Ocean”, but there is still no evidence to suggest that the UFO-like object is an alien ship.

Volker Bruchert, an associate professor of geology at Stockholm University, told Life’s Little Mysteries.com: “My hypothesis is that this object, this structure was formed during the Ice Age many thousands of years ago.”

But Lindberg and Asberg claim the samples they gave for analysis weren’t from the object itself, but from the “vicinity” of the object”, according to Open Minds.tv.

It seems that nobody wants to fund research into the Baltic Sea discovery. The question remains: what really lies beneath?

This story originally appeared in The Sun.