Answer: A Pine Tree

The oldest organism ever discovered was a pine tree, specifically a Great Basin Bristlecone Pine–a species of pine tree known for their hardiness and longevity. The particular Great Basin Bristlecone Pine in question was cut down in 1964 specifically because it had grown so old and hardy.

Graduate student Donald Rusk Currey was taking core samples from trees in the area for his research. When he came upon the old Bristlecone (the tree would later be renamed Prometheus), he couldn’t get a clean core sample and broke multiple tools in his attempts. Forest Service personal suggested he fell it and examine the core of the tree directly. He took them up on the advice, and upon felling the tree he discovered that it was much older than he had estimated–the extant rings indicated the tree was at least 4,862 years old and possibly much older, making Prometheus the oldest non-clonal organism in the world at the time of its death.