There are two ways to remove coal from the ground: surface mining and underground mining. Surface mining is used when a coal seam is relatively close to the surface, usually within 200 feet. The first step in surface mining is to remove and store the soil and rock covering the coal (called the overburden).
Pearl oysters are not closely related to true oysters, being members of a distinct family, the feathered oysters (Pteriidae). Both cultured pearls and natural pearls can be extracted from pearl oysters, though other molluscs, such as the freshwater mussels, also yield pearls of commercial value.
Zinc: 32 mg in 6 raw oysters (400% of your RDA!) Other body benefits: These slippery bivalves also offer a dose of protein and heart-healthy omega-3 fatty acids. They're also rich in iron, a mineral needed to transport oxygen throughout the body. Best ways to eat them: No matter how you have them, oysters are one of the best sources of zinc you can eat.