Marble rocks forms when limestone undergoes metamorphism.
Marble rock is formed from the limestones,when the limestone is influenced by heat and tremendous pressure it transforms in marble through a method called metamorphism.
During the metamorphism, limestone gets recrystallizes and result in the formation of interlocking carbonate mineral crystals that form the marble.
The only shape that casts a round shadow no matter which direction it is pointed is a sphere, and the ancient Greeks deduced that this must mean the Earth is spherical.
