Gigantic virus
Found in a sample of deeply buried permafrost soil from Siberia, was more than 30,000 years old, and is bigger than some bacteria.*Pithovirus sibericum*
Although it spent a millennia in a deep freeze, it can still infect single cell organisms. It is 30% bigger than the Pandovirus, the largest known contemporary virus, but has a much smaller genome.
"60% of its gene content does not resemble anything on Earth."
March 18, 2014 issue of Proceedings of the National Academy of Sciences.