(Mytilus trossulus) or (Mytilus californianus)
Mussels are found in dense mats attached by fine threads to rocks, pilings, or other hard surfaces. Mussels have oblong, blue-black or brown shells Of the two species of mussels found in Washington waters, the foolish common blue or bay mussel (Mytilus edulis) is the most commonly used for food. It grows to a length of about three inches and is found mainly in sheltered waters attached to gravel, boulders, floats, and piling. The California mussel grows to a considerably larger size and is found primarily on wave-washed rocks in coastal areas, the Strait of Juan de Fuca, and the San Juan Islands, can grow to over six inches. Mussels are detached, scrubbed clean, and then steamed or cooked like clams.
Mussels are prized by gourmet cooks as an essential ingredient of seafood dishes such as bouillabaisse and paella. A more conventional method of preparation is to steam them either in salted water or a broth seasoned with wine, garlic, olive oil, and various spices. Before cooking, wash and scrub the shells several times in fresh water, discarding open or broken mussels and whatever debris that might be attached. The byssus, or "beard," can be removed by pulling it toward the pointed end of the mussel shell, although some shellfish connoisseurs prefer to leave it attached, using it as a built-in fondue fork. The meat of the mussel tastes similar to oysters, and some even consider the mussel superior.
As with all bivalves, caution must be exercised to avoid contaminated mussels. Do not take shells from areas that are subject to pollution and avoid mussels that grow on recently creosoted pilings. Check current regulations regarding closures during warmer months in the coastal and Straight of Juan de Fuca area (see Washington Department of Health's website for Emergency Shellfish Closures Due to Red Tide and Other Marine Biotoxins)