In what they are calling the most extreme case of frozen plant regeneration ever documented, scientists are claiming to have regrown shoots of Antarctic moss that were trapped seemingly lifeless beneath layers of ice and frost from the days of Attila the Hun.

In a paper in the journal Current Biology, scientists from the British Antarctic Survey and the University of Reading, in England, said the regrowth occurred in a sample taken from a bank of moss on Signy Island, which is 375 miles off Antarctica and has an environment too harsh to support a single tree.

The moss was about 1,600 years old, black and looked dead. But when it was thawed in a lab's incubator, something happened. It grew again.

The moss, Chorisodontium aciphyllum, can grow into high banks more than 9 feet tall. Co-author and terrestrial ecologist Peter Convey said the moss was visibly greening with new shoots after three weeks. He said scientists didn't do anything to make it grow except squirt it with distilled water.

"These mosses were basically in a very long-term deep freeze," Convey wrote. "This time scale of survival and recovery is much, much longer than anything reported for them before."

Cryptobiosis is a term meaning "hidden life" and describes the ability of some invertebrates, plants and microbes to enter a state of suspended animation when faced with environmental extremes, such as intense cold or lack of moisture.

Many scientists have believed that cryptobiotic organisms could survive in such a state for no more than a couple decades. "Here we show unprecedented millennial-scale survival and viability deep within an Antarctic moss bank preserved in permafrost," Convey and his colleagues wrote.

He said this is by far the longest case of revival of a plant or animal from frozen limbo. "The potential clearly exists for much longer survival," the authors wrote.

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