We repurpose discarded oyster shells to produce PCC without calcination and pearltide, driving circular economy and sustainability. Oyster shell-derived biocalcium can completely replace mineral calcium, reducing environmental damage from mining. Recycled PCC is used in cosmetics, plastics, and paper packaging, reducing carbon emissions by 74% and 81% compared to virgin plastics. Pearltide offers natural moisturizing, repairing, and anti-aging benefits for cosmetics.