The giant sequoia had been classified in the same genus as the coast redwood, but now has its own genus, Sequoiadendron giganteum. Not as tall as the coast redwood, nor manifesting the extensive trunk of the tropical African trees, the giant sequoia is nevertheless the most massive living thing. It rises to a height of 325 feet (99 m) and has a diameter of 30 feet (9 m). Such trees may weigh up to 6,000 tons. The immense size implies considerable age. Some giant sequoias are estimated to be more than 3,500 years old. The big tree has a fibrous, furrowed, reddish -brown bark that may exceed 20 inches (50 cm) in thickness. Once widely harvested for their wood, giant sequoias are few in number. Fortunately, giant sequoias are protected in parks.