"Ahu" are stone platforms on which many moai sit. There are 313 known ahu and 125 of these carry moai. The biggest, Ahu Tongariki is 220 m (720 ft), and had the most (15) and tallest moai.
Plants and animals struggle to survive under the extreme conditions of Mt Everest but birds have been seen at high altitudes and a type of moss grows at heights close to 6500 m (21325 ft).