The seashell, especially the scallop, is the symbol of baptism in Christianity. The baptismal font is often shaped like a scallop, or decorated with one. The dish used by priests to pour water over the heads of catachumens in baptism is often scallop-shaped. The scallop, too, is the symbol for the Apostle James the Greater. St. James used the scallop shell during his pilgrimage to beg for food and water. Even the poorest people could fill the small shell, so he always found help along his way. Later, followers of St. James wore the scallop-shell symbol on their hats and clothes and it became the symbol of pilgrimage. CHRISTIAN SCALLOP SHELL 
Fertility is also associated with the scallop shell, as exemplified in ancient and renaissance paintings of Venus, the Roman goddess of fertility and love. She is often shown coming out of a scallop shell. Perhaps this is why some pilgrims, walking the way of St. James, used the scallop in a pagan ritual to encourage child-bearing.