"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.
Humans can hear the difference between hot and cold water being poured, this is apparently vital for advertising purposes. Cold water doesn't sell tea I suppose.