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.
- Harbo, Rick M., 1997. ;Shells and Shellfish of the Pacific Northwest: ; A Field Guide. ;Harbour Publishing, Madeira, BC. Canada. ; ISBN 1-55017-146-1. ;Paperback, 271 pp. ; The front of this book has color photos and briefdescriptions of mollusks and brachiopods found in the northwest. ;The latter part of the book has somewhat more detailed descriptions keyedto the color photos. ; Organized taxonomically. http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Annotated_Bibliography.html#Harbo+1997
- Morris, Percy A., 1966. ;Pacific Coast Shells. ; Peterson Field Guide. ; 297 pp, paperback. ;Houghton Mifflin Co., Boston. ; ISBN 0-395-08029-0. ; Brief descriptionsand mostly black-and-white photos of hundreds of shells found on the NorthAmerican Pacific coast. http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Annotated_Bibliography.html#Morris+1966
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