| http://www.w3.org/ns/prov#value | - One of the most beautiful and impressive of the many and varied defence mechanisms that occur in nature is the creation of pearls ??? generated when foreign particles such as sand grains or parasites get inside the soft bodies of oysters, clams or mussels.When defences are breached, these organisms respond by coating invaders in nacre, a hard iridescent material also known as mother of pearl.
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