A hard rigid usually calcareous covering or support of an animal, as a mollusk. Many varieties of shell were used in antiquity, apart from the use of their contents as food. Some were used for tools (oyster, conch) and others were made into jewelry or used for decorative inlays. Others, such as ostrich and smaller seashells, were used to make beads. Shell was perforated and strung on necklaces since at least the Upper Palaeolithic. It is frequently found in tombs, probably symbolizing the resurrection. Shell was traded widely to areas where it was not locally available.