Eggshell is the hard outer covering of an egg, primarily composed of calcium carbonate. It serves as a protective barrier for the developing embryo inside, providing both strength and a degree of flexibility. The color of eggshells can vary, typically ranging from white to brown, depending on the breed of the chicken. The thickness of an eggshell can also differ, influenced by factors such as the age and diet of the hen. A healthy eggshell is smooth and free from cracks, which helps maintain the freshness of the egg and protects it from bacteria.