What Makes A Conker Hard?

A conker becomes hard due to the maturation process of the seed from the horse chestnut tree. As the seed dries out, it undergoes changes in its internal structure, leading to increased density and hardness. The hard outer shell, called the pericarp, also contributes to its toughness, protecting the seed inside. Additionally, environmental factors and the seed's exposure to air play a role in its hardening process.