Greenland sharks are now the longest-living vertebrate animals (that we know!). By using radiocarbon dating on the eye lens cells of 28 Greenland sharks, researchers found that the oldest of the bunch was 392 (plus/minus 120) years old.
Further reading:
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Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus) http://science.sciencemag.org/content/353/6300/702
the Runaway Lab Book 