Oysters have two thick, irregular valves, but one of them (the left) is usually cemented to the substrate (or to another oyster, as above). The valves are usually higher than long, have no "wings" near the hinge, and have no regularly spaced radial ribs. Crassostrea gigas grows up to 25 cm high and has conspicuous frills on its valves. Gray-white shell; often new growth is purplish-black. Inside is smooth and white. The left valve is usually larger and cupped, while the upper (right) valve is usually slightly smaller and flat.