Steamer clams, also called Mya arenaria, soft-shell clams and Ipswich clams, have very thin, fragile shells. Like other clams, they are sold live and should only be cooked and eaten from that state. Test whether a steamer clam is alive by rapping its shell lightly with a finger; if it closes, it is alive. Discard any dead clams immediately, or if you are in a store, report them to the fishmonger. When stored in ideal conditions, steamer clams will stay fresh for about a week to 10 days.
Clear a space at the back of your refrigerator where the temperature is around 36 degrees Fahrenheit.
Place the clams in a box or other container if they did not come in one, then spread them out in a single layer, if possible, between two damp towels and put them in the refrigerator.
Flip the clams over gently every day if they are not in a single layer. Redistribute the weight of the clams so that no clams are constantly bearing the weight of all the others, since the shells are very fragile.