Scientists discovered, and successfully brought back to life, shrimp-like animals embedded at the bottom of South Center Lake in Minnesota. The animals are scientifically called Daphnia and are more commonly known as water fleas.
"About as big as a grain of rice, the shrimp live by the billions in lakes. Each fall, some species produce eggs sealed in tough cases. The cases fall to the bottom of lakes, and the next spring many produce new water fleas. But some cases get buried in sediment, their eggs unhatched.
In 2009 Dr. Weider, now at the University of Oklahoma, and his colleagues set out to resurrect eggs from some lakes in Minnesota. The chemistry of those lakes has been carefully documented for decades, making it possible to see how changes in pollution levels affected the water fleas.
To gather the animals, Dr. Weider and his colleagues took a boat out on the lakes. 'It’s a smaller version of a party barge, with a hole cut out of the deck,' he said.
Through the hole, the scientists lowered a tube and pushed it about three feet into the sediment — deep enough, Dr. Weider thought, to gather water flea eggs a few decades old.
The scientists then went back to Oklahoma, sifted the cases from the mud, and started resurrecting the animals. They also extracted Daphnia DNA, giving them more data to analyze.
Only then did Dr. Weider get an estimate for the age of the sediment in South Center Lake from another lab.
'I said, ‘Are you kidding me?'' said Dr. Weider.
The lab concluded that the bottom of the lake’s sediment core was about 1,600 years old. The oldest eggs that Dr. Weider and his colleagues had successfully hatched were about 700 years old." - Carl Zimmer, January 8, 2014, The New York Times, http://www.nytimes.com/2014/01/09/science/a-living-time-capsule-shows-the-human-mark-on-evolution.html?_r=0