Unless in a garden or farm, corns do not grow from seeds. Joking aside, corns on feet do not grow from a seed or root. A corn is a thickening of skin in response to pressure. For instance, a shoe that is too narrow can press against a toe, resulting in pressure which causes the skin to react by thickening and forming a corn.

Many corns occur regardless of how "good" a shoe is. A bone in the toe is often causing pressure internally. This could be from arthritis, bone spurs, or a contracture of the joint known as a hammertoe. The pressure from the bone also forms the conical area of hard, dead skin called a corn. Treatment for this includes padding and wearing shoes with more room inside. Surgery to remove the pressure from the bone is often the best definitive treatment for a persistent corn.