Ark shells are a family of medium to large edible marine clams, a bivalve shellfish found in sandy coastal waters throughout the world. They can have a rectangular or oval shell and include Noah's ark. and are generally available pickled in brine or vinegar. However, they can be found fresh in some parts of the world, in which case they can be eaten either raw or steamed for around five minutes and checked in the same way as you would mussels and often served as part of a pasta dish. They are inclined to be tough and chewy.