<<photo14.jpg>> Its shells are about 40mm long and 30mm high with big ones reaching up to 60mm in length.  The shell is swollen egg-shaped oval and hard.  The spiral grooves (wrinkles across the growth line) on the surface are very visible on the front and back and display netted veins intersecting the growth veins.  The peelings are rough and their size, pattern and shape differ from region to region.   

The umbo is slightly bent to the front and the tendons are very visible.  The tentacle is simple with no projections.  The colors vary greatly and some have different left and right shells.  It has three major teeth and the edges of the outer shells are relatively deeply cut.   

They grow in the sands and mud of inner bays.  The young clams are not much swollen and grow attached rocks.  They hatch from early summer to early autumn and grow twice a year in May and in Oct¡­Nov.  As they grow and reproduce fast, they are also cultured.  From every 1§³, about 0.5¡­5kg clams can be collected.  When grown for a year, their become 1.5¡­1.6 times longer and 2.9¡­3.5 times heavier.  The sandy wetlands with many pearly pebbles exposed 4~5 hours during ebb tides are great for baby clams.   

They can be salted or cooked, but avoid having them from late spring to early summer during their growth, because they may be poisonous.  They have been widely cultured and are increasingly demanded for exported canned foods.  They are the kind of clam most enjoyed by Koreans.