I hate facts. They get in the way of just so much…
Scientists calculated the age of the plants from DNA tests on clumps gathered from the seafloor between Spain and Cyprus.
They revealed the typical age of the seagrass, Posidonia oceanica, to be thousands or tens of thousands of years old, though some appeared to more ancient still. A 15km-wide stretch of seagrass lying in waters off the Spanish island of Formentera could be 200,000 years old, the scientists found, dating it to the late Pleistocene and the dawn of humanity.
Until now, a contender for the oldest living organism was a Tasmanian seagrass thought to live more than 40,000 years. (here)