Hello, I'm an expert in the field of biology and evolution. When it comes to the oldest living species on Earth, we often refer to organisms that have remained relatively unchanged over millions of years, indicating a long evolutionary history.

The Antarctic sponge (*Laodicea sp.*) is considered one of the oldest living species, with some individuals living for over 1,500 years. These sponges inhabit the deep waters around Antarctica and have a slow growth rate, which contributes to their longevity.

Another contender for the title is the ocean quahog clam (*Arctica islandica*). This species is known to live for over 500 years, with the oldest recorded individual, named Ming, having lived for 507 years before it was unfortunately killed during a scientific study.

In the plant kingdom, the Posidonia oceanic grass is also remarkably old, with some underwater meadows thought to be over 100,000 years old, although the individual blades are not that old.

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Here the list of top 10 oldest animal species on Earth.7 Sturgeon �C 200 million years old. ... 6 Coelacanath �C 360 million years old. ... 5 Horseshoe Crab �C 445 million years old. ... 4 Nautilus �C 500 million years old. ... 3 Jelly Fish �C 550 Million years old. ... 2 Sponge �C 580 million years old. ... 1 Cyanobacteria �C 2.8 billion years old.More items...read more >>