They are some of the longest living creatures on the planet. Their longevity means that if you visit the Galapagos today, you might look into the eyes of a Tortoise that Charles Darwin met, when he visited the island for his revolutionary research in the 1880’s.
Giant tortoises might also hold the secret to immortality, as they don’t seemingly die from old age. A giant tortoise died in 2006, and carbon dating of his shell confirmed that he had been born around 1750. It wasn't old age that killed him - he died of liver failure complicated by a wound brought on by a crack in his shell. If his handlers had had the resources and inclination to arrange for a liver transplant and surgery to rebuild his shell, it's possible he might still be crawling around today.
Scientists are currently studying this phenomenon and what it might mean for humans!