The oldest living thing on Earth has been discovered to be a self-cloning seagrass in the Mediterranean.

Carlos Duarte of the University of Western Australia studied the DNA of the seagrass Posidonia oceanica at 40 different sites across Spain and Cyprus, reported UPI.  

They have never experienced the speed of climate that the Mediterranean is currently experiencing, said Duarte, according to UPI. Researchers believe that the seagrass could at least 100,000 years old.

The reason why Posidonia oceanica has lived so long is because of how it reproduces. Posidonia oceanica reproduces asexually, by cloning.  Each strand of seagrass is genetically identical to the next and therefore is considered one organism. Posidonia oceanica also lacks any major predators, allowing it to flourish along the seafloor. Because of these factors, it is estimated that there are nearly 2,100 miles of meadows across the seafloor.

They are continually producing new branches. They spread very slowly and cover a very large area giving them more area to mine resources, said Duarte, according to the Daily Telegraph. They can then store nutrients within their very large branches during bad conditions for growth.

One patch of Posidonia oceanica off the island of Formentera near Spain was identical to about 9 miles off the coast. However, despite its ability to reproduce and its longevity, the case study, written by Duarte and his colleagues, outline problems with that Posidonia oceanica.

They support important marine ecosystems that rank among the most valuable on earth in terms of biodiversity and production, but are experiencing a worldwide decline, said the case study. Climate change is posing a threat the Posidonia oceanica. It is estimated that the water in the Mediterranean is warming three times faster than the global average, meaning Posidonia oceanica meadows decline about 5 percent annually.

They have never experienced the speed of climate that the Mediterranean is currently experiencing, said Duarte.