But the individual parts of the sponge ball are moving from their position.

However if you are holding a pre-compressed ball, and maintaing the compression, then no work is done.

Your argument might have been true if the ball was rigid and compressible. But it's not.

But the individual parts of the sponge ball are moving from their position.

However if you are holding a pre-compressed ball, and maintaing the compression, then no work is done.

Your argument might have been true if the ball was rigid and incompressible. But it's not.