<image>Lingling's family has a rectangular glass fish tank with a length of 8 decimeters, a width of 4 decimeters, and a height of 7 decimeters. There was originally some water in the tank (as shown in Image 1). After putting in 4 identical decorative balls (as shown in Image 2), the water level rose by 6 centimeters. What is the volume of each decorative ball in cubic centimeters?
