 Bivalves have long been a part of the diet of coastal human populations . Oysters were cultured in ponds by the Romans , and mariculture has more recently become an important source of bivalves for food . Modern knowledge of molluscan reproductive cycles has led to the development of hatcheries and new culture techniques . A better understanding of the potential hazards of eating raw or undercooked shellfish has led to improved storage and processing . Pearl oysters ( the common name of two very different families in salt water and fresh water ) are the most common source of natural pearls . The shells of bivalves are used in craftwork , and the manufacture of jewellery and buttons . Bivalves have also been used in the biocontrol of pollution . 
