Giant tortoises are among the world's longest-living animals, with an average lifespan of 100 years or more. The Madagascar radiated tortoiseTu'i Malila was 188 at death in Tonga in 1965. Harriet (initially thought to be one of the three Galápagos tortoises brought back to England from Charles Darwin's Beagle voyage but later shown to be from an island not even visited by Darwin) was reported by the Australia Zoo to be 176 years old when she died in 2006. Also, on 23 March 2006, an Aldabra Giant Tortoise named Adwaita died at Alipore Zoological Gardensin Kolkata. He was brought to the zoo in the 1870s from the estate of Lord Robert Clive and is thought to have been around 255 years old when he died. Around the time of its discovery, they were caught and killed for food in such large quantities that they became virtually extinct by 1900. The giant tortoise is now under strict conservation laws and is categorised as an endangered species.