A 176-year-old tortoise believed to be one of the world’s oldest living creatures has died in an Australian zoo. "Harriet" was long reputed to have been one of three tortoises taken from the Galapagos Islands by Charles Darwin on his historic 1835 voyage aboard the HMS Beagle. Crocodile hunter Steve Irwin, right, and his wife Terri pose in an undated photo with Harriet, a Giant