abstract age aged appearance armor armored armorment armour armoured armourment astrochelys-radiata carapace critically-endangered endangered giant tortoise herbivore hide large tortoise leathery longevity Madagascar old plod plodding protection protective radiated-tortoise reptile reptilian rough scaly shell size skin slow strength strong texture textured textures tortoise tough zoo african broad-mouthed collagen creases 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 white rhinoceros wide-lipped rhinoceros aldabra giant tortoise aldabrachelys gigantea eating eating grass elongated neck neck Seychelles wrinkled wrinkles antler-like horns blotched blotches brown browsers camelopard coat coloring colors colouring colours creamy lines feeding giraffe knobs legs long-legged long-necked long-tongued mottled ossicones ossified cartilage patches patterned rectangular spots rothschild's giraffe ruminant spread legs strong tongue tallest