Earlier this month, a mysterious purple goo began to coat Norway's northern coast – and scientists are still investigating what it might be. Initial reports suggested that the substance, which has been described as "margarine-like", is the result of thousands of partially decomposed jellyfish. (We know it's true origin ... here's looking at you, Ivan Ooze.)

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All jokes aside, the most likely culprit is the cigar comb jellyfish, also known as the cucumber jelly (Beroe spp.), which has appeared in large numbers in both Norway's Lyngen and Kvænangen fjords. Arctic University of Norway associate professor Roger B. Larsen and his team have been surveying the area since fishermen first spotted the jellies offshore back in August.  

"I have some samples of the red-pink slime, and it will hopefully be analysed at the end of the month," he tells us via email.

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It appears that the slime (right) is the result of decaying cucumber jellies (left). Image via Roger B. Larsen

Millions of cubic metres of the fjords have been affected, which poses a problem for fishermen who rely on sonar to locate their catch. Because the slime has formed a thick band deep in the water column, some 15 metres above the seafloor, it's picked up by electronic instuments as though it were a dense school of fish. 

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Image via Roger B. Larsen
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Image via Roger B. Larsen

According to Larsen, an underwater recording in the area has also detected large blooms of siphonophores – gelatinous, colonial organisms that often resemble jellyfish. "These [animals] hold some gas-filled bladders and they might be the reason for the extremely strong sonar echoes close to the seabed." (Perhaps the most infamous of the siphonophores is the Portuguese man-o-war or "blue bottle".) 

Trawl samples in the fjords resulted in almost no fish and shrimp, despite the area being known as an abundant fishing ground. "I've done annual cruises with my students here in the past, and have never seen anything like this," adds Larsen. "It is obvious that there is something going on which [the] wildlife [is] unable to cope with."

To make matters more mysterious, the team also hauled up a mass of an unidentified, marble-like jellyfish, which they have dubbed "glass eggs". The samples will be analysed by the scientists at the Institute of Marine Research. "The species is new to me," he says. "They're round, have no visible tentacles and a four-part yellow core." 

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Image via Roger B. Larsen