age aged aldabra giant tortoise aldabrachelys gigantea armor armored armorment armour armoured armourment carapace eating eating grass elongated neck giant tortoise herbivore hide large tortoise leathery longevity neck old plod plodding protection protective reptile reptilian Seychelles shell size skin slow strength strong texture textured textures tortoise zoo african broad-mouthed collagen creases endangered flat-mouthed folds gray grazer grey heavy herbivorous horns keratin large lattice structured mammal megafauna odd-toed ungulate perissodactyl placid powerful rhino rhinoceros snout southern white rhinoceros square-lipped rhinoceros thick threatened tough white rhinoceros wide-lipped rhinoceros bark barking black-&-white black-coats black-skin Bray braying Camouflage common-zebra contrast contrasting equids equus-quagga-boehmi erect-manes family-groups fast grant’s-zebra grazers harems herbivores herd herds individual mammals mohawk-like-manes patterns plains-zebra social stiff-manes stripes subspecies ungulates unique unique-stripe-patterns white-fur white-stripes zebra