Sink holes in the Thunder Bay region of Michigan, several hundred feet deep, are exposed to the ancient, mineral rich Paleozoic era bedrock, where the minerals leech out into the water creating a very dense, mineral rich, oxygen free underwater eco-system.

“You have this pristine fresh water lake that has what amounts to materials from 400 million years ago … being pushed out into the lake,” said Steven A. Ruberg,

Similar to the undersea vents, these sink holes harbor odd bacteria adapted to extreme environments. They grow in large "pony-tails" or in purple towers along the bottom.

The Lake Huron sinkholes are dominated by brilliant purple mats of cyanobacteria -- cousins of microbes found on the bottom of permanently ice-covered lakes in Antarctica -- and pallid, floating pony-tails of other microbial life, according to the journal article. The saltwater venting out of the sinkholes is hostile to most life forms because it lacks oxygen, the scientists said in the article.. --article

Video found at the Annis Water Resources Institute site on the Sinkhole Ecosystem Project page.

For those out there who feel Lake Huron is the unsung third wheel of the largest Great Lakes, this is it, baby. This is pretty darn cool. Researchers believe these sink holes might also be found in Lake Superior and Lake Michigan, but so far that's just a hypothesis. Right now they appear to be unique to Lake Huron.

And they've been right under our noses this whole time, and not even that far from shore, looks like. The Great Lakes have been sorely un-explored and under-researched for too long. They've just been part of the scenery, used to transport goods and raise fish for eating. It's discoveries like this that should make people sit up and pay attention to the wonders in their back yards...and more importantly, it's discoveries like this that should warrant greater interest in researching the Great Lakes and fanning the urgency of Great Lakes preservation efforts and funding.

Because it's just so frickin' COOL.

Additional reading thanks to Kos user Ellicatt

Life at the very bottom (skip)

In this case, scientists wonder if the microbes may be truly primordial. Researchers found that the purple bacteria can photosynthesize as easily in sulfur-rich water as they can in fresh water, an ability suited to the dim and sulfur-rich conditions of shallow, primeval seas that existed billions of years ago.

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Cameras on the submersible recorded something divers had seen and talked about for years—vast purple carpets mottling the bottom of the shallower sinkholes, where dim surface light still reaches. In deeper, darker water, the submersible found white microbial mats similar to those around deep-ocean heat vents. One thing the researchers tried to figure out was what on Earth those purple colonies were. They found that the single-celled microbes banded together to form filaments that in turn joined to form mats. When debris fell on the mats, the bacteria got on top of it by crawling toward the light. The sticky ooze could climb a pebble in a laboratory water tank in a few hours, and crawled up the sides of beakers.