Scientifically how? on Instagram: "How are pearls formed: Pearls form inside oysters and other mollusks when an irritant, such as a grain of sand, gets trapped inside the shell. The mollusk secretes layers of nacre, a combination of calcium carbonate and protein, around the irritant to protect itself. Over time, these layers build up to form a pearl. #pearls #gemstone #pearls #science #sciencefacts #trending #viral #viralvideos #trendingvideos #facts #defend #instagram"