"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.
The phrase 'off with the crack of the bat', while romantic, is really meaningless, since the outfielder should be in motion long before he hears the sound of the ball meeting the bat.