Eggshells are the hard outer covering of an egg and are made mostly of calcium carbonate, along with small amounts of other minerals. Benefits of eggshells Strong source of calcium – Helps support strong bones and teeth when properly cleaned and prepared. Supports bone health – Calcium from eggshells can help reduce the risk of weak or brittle bones. Aids joint health – Provides minerals that support healthy joints and cartilage. Improves soil fertility – Crushed eggshells add calcium to soil, helping plants grow stronger. Natural household use – Can be used as a gentle abrasive for cleaning utensils and surfaces.