A Swedish expedition team has been left perplexed by an oddly-shaped object that they found at the bottom of the Baltic Sea.
The sonar picture of the unidentified object resembles the famed 'Star Wars' ship the Millennium Falcon.
The divers found that the object was raised about 10-13 feet above the seabed and curved in at the sides, giving it a mushroom shape.
They added that the object has 'rounded sides and rugged edges'
"First we thought this was only stone, but this is something else," the Daily Mail quoted diver Peter Lindberg as saying in a press release.
At the center of the object, which has a 60-meter idameter, has an 'egg shaped hole leading into it from the top'.
Surrounding the hole, they found a strange, unexplained rock formation. Adding fuel to the speculative fire, they said that the rocks looked 'like small fireplaces' and the 'stones were covered in something resembling soot'.
"Since no volcanic activity has ever been reported in the Baltic Sea the find becomes even stranger," Lindberg continued.
A brief video clip of the dive was released to Swedish-language paper Expressen and can be viewed on Gizmodo.
The soot also proved cause for concern for Lindberg's colleague on the Ocean X explorer team, Stefan Hogeborn.
"During my 20-year diving career, including 6,000 dives, I have never seen anything like this. Normally stones don't burn," Hogeborn said in the release.
"I can't explain what we saw, and I went down there to answer questions, but I came up with even more questions," he added.
Another find that they saw in person for the first time was the 985-foot trail that they described 'as a runway or a downhill path that is flattened at the seabed with the object at the end of it'.
The object was first found this month last year, but because of a lack of funding and bad timing, they have were not able to pull a team together to see for themselves - just the strange, metallic outline, and a similar disk-shaped object about 200 metres away.
As it was before the recent dive, the story behind the object is anyone's guess.
"We've heard lots of different kinds of explanations, from George Lucas's spaceship - the Millennium Falcon - to 'it's some kind of plug to the inner world,' like it should be hell down there or something," Lindberg said.
While the Ocean Explorer team is understandably excited about their potentially earth-shattering find, others are slightly more sceptical and are questioning the accuracy of the sonar technology.