"It's definitely, by the smell and the makeup of it, it's some sort of naturally occurring organic or otherwise marine organism."

Something else: No one in Barrow or Wainwright can remember seeing anything like this before, Brower said.

"That's one of the reasons we went out, because in recent history I don't think we've seen anything like this," he said. "Maybe inside lakes or in stagnant water or something, but not (in the ocean) that we could recall ...

"If it was something we'd seen before, we'd be able to say something about it. But we haven't ...which prompted concerns from the local hunters and whaling captains."

The stuff is "gooey" and looks dark against the bright white ice floating in the Arctic Ocean, Brower said.

"It's pitch black when it hits ice and it kind of discolors the ice and hangs off of it," Brower said. He saw some jellyfish tangled up in the stuff, and someone turned in what was left of a dead goose -- just bones and feathers -- to the borough's wildlife department.

"It kind of has an odor; I can't describe it," he said.

Hasenauer said he hasn't heard any reports of waterfowl or marine animals turning up.

Brower said it wouldn't necessarily surprise him if the substance turns out to be some sort of naturally occurring phenomenon, but the borough is waiting until it gets the analysis back from the samples before officials say anything more than they're not sure what it is.

"From the air it looks brownish with some sheen, but when you get close and put it up on the ice and in the bucket, it's kind of blackish stuff ... (and) has hairy strands on it."

Hasenauer said the Coast Guard's samples are being analyzed in Anchorage. Results may be back sometime next week, he said.

The two Coast Guard experts sent up to overfly the area with the borough said they saw nothing that resembled an oil slick, Hasenauer said.

"We brought back one sample of what they believe to be an algae," he said, and a big algae bloom is one possibility.

"It's textbook for us to consider algae because of all the false reports of oil spills we've had in the past. It's one of the things that typically comes up" when a report turns out not to be an oil spill after all.

But, he said, "there's all types of natural phenomena that it could be."

Meanwhile, the brownish-blackish gunk is drifting along the coast to the northeast, Brower said.

"This stuff is moving with the current," he said. "It's now on beyond Barrow and probably going north at this point. And people are still encountering it out here off Barrow."

For the most part, the mystery substance seems to have stayed away from shore.

"We did get some residents saying it was being pushed against the shoreline by ice in some areas," Brower said, "but then we get another east wind and it gets pushed back out there."

The largest dead squid on record measured about 60ft including the length of its tentacles, but no one knows how big the creatures might grow.

For years sailors have told tales of monsters of the deep including the huge, many-tentacled kraken that could reach as high as a ship's mainmast and sink the biggest ships.

However Phil Lobel, a marine biologist at Boston University, Massachusetts, doubts that giant squid are the source of Bloop.

"Cephalopods have no gas-filled sac, so they have no way to make that type of noise," he said. "Though you can never rule anything out completely, I doubt it."

Nevertheless he agrees that the sound is most likely to be biological in origin.

The system picking up Bloop and other strange noises from the deep is a military relic of the Cold War.

In the 1960s the U.S. Navy set up an array of underwater microphones, or hydrophones, around the globe to track Soviet submarines. The network was known as SOSUS, short for Sound Surveillance System.

The listening stations lie hundreds of yards below the ocean surface, at a depth where sound waves become trapped in a layer of water known as the "deep sound channel".

Here temperature and pressure cause sound waves to keep travelling without being scattered by the ocean surface or bottom.

Most of the sounds detected obviously emanate from whales, ships or earthquakes, but some very low frequency noises have proved baffling.

Scientist Christopher Fox of the U.S. National Oceanic and Atmospheric Administration's Acoustic Monitoring Project at Portland, Oregon, has given the signals names such as Train, Whistle, Slowdown, Upsweep and even Gregorian Chant.

He told New Scientist that most can be explained by ocean currents, volcanic activity -- Upsweep was tracked to an undersea South Pacific mountain that had not been identified as "live."

"The sound waves are almost like voice prints. You're able to look at the characteristics of the sound and say: 'There's a blue whale, there's a fin whale, there's a boat, there's a humpback whale and here comes and earchquake," he says.

But some sounds remain a mystery he says. Like Bloop -- monster of the deep?

Listen to the bloop and read more here: http://en.wikipedia.org/wiki/Bloop