Earth's Oldest Living Thing Is... Giant seagrass, called 'Posidonia oceanic,' likely at least 100K years old By Evann Gastaldo, Newser Staff Posted Feb 7, 2012 9:22 AM CST Updated Feb 11, 2012 7:15 AM CST 37 comments Comments A stock image of seagrass. (Shutterstock) (Newser) – The 43,000-year-old Tasmanian plant once identified as the planet's oldest living thing turns out to be a relative youngin'. At up to 200,000 years old, patches of giant seagrass in the Mediterranean have taken the top slot. Australian scientists sequenced the DNA of the Posidonia oceanic to find that it is between 12,000 years and 200,000 years old, and most likely at least 100,000 years old. Their report, published in PLos ONE, reviewed 40 underwater meadows throughout the Mediterranean. The seagrass has survived so long because it has the ability to clone itself, reproduce asexually, and stockpile nutrients for tough times, the Telegraph notes. "They are continually producing new branches," says a professor. But climate change threatens the seagrass, he adds, because "as the water warms, the organisms move slowly to higher altitudes. The Mediterranean is locked to the north by the European continent. They cannot move. The outlook is very bad."