Giant Sequoia

The most massive living thing on Earth/Plants

Giant sequoias (Sequoiadendron giganteum) are the largest trees by volume on the planet. General Sherman, the biggest, contains enough wood to build 40 five-room houses. Their bark can be 60 cm thick and is virtually fireproof, which is handy because they actually depend on periodic fires to reproduce. Some living specimens started growing before the Roman Empire existed.