The Greenland shark reigns supreme in the longevity department among vertebrates, with lifespans estimated to be between 250 and 500 years! Scientists attribute this extended lifespan to a combination of factors:

* **Slow metabolism:** The frigid, deep waters where Greenland sharks dwell necessitate a sluggish pace of life. This low metabolic rate translates to a slower burning of energy, potentially reducing cellular wear and tear. Their slow metabolism is also reflected in their languid movements and  growth rate of about 1 centimeter a year.
* **Minimal predation:** With no natural predators except for other Greenland sharks (on rare occasions), these sharks face minimal threats throughout their lives. This reduces stress and the potential for fatal injuries.
* **Unique proteins:**  Recent research suggests that Greenland sharks might have  distinctive proteins involved in DNA repair, like the H2AX protein, which could contribute to their extended lifespans. 

While the exact reasons are still being explored, these factors likely come together to create the perfect recipe for the Greenland shark's remarkable longevity.