6. Greenland Shark
The Greenland shark is a deep-sea marvel, known as one of the longest-living vertebrates on Earth. Scientists have dated some individuals at over 400 years old, making them true Methuselahs of the ocean.
Their secret seems to lie in their exceptionally slow metabolism and the chilly temperatures of the Arctic waters they inhabit. According to Science Magazine, these factors help keep their bodies—and their aging process—moving at a glacial pace.