"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.
I speak onstage to try to establish some method of communication. The songs are supposed to be a way of communicating. But speech and drinks and sometimes chocolates are also a way of communicating.