"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 think the water dictates how food will taste in a country. In England the apples taste unlike apples grown in any other place. England is an island, there's a lot of salt in the air and in the water. I think that has something to do with it.