During medieval times, the Christian pilgrims who traveled La Route de Saint-Jacques de Compostelle (in Spanish El Camino de Santiago de Compostela and known in English as the Way of Saint James) carried a scallop shell as a badge and essential accessory of their pilgrimage. The shell had been associated with the stories and legends about Saint James and thus was adopted by the pilgrims to Compostela who wore it on their clothing and often used it as a handy scoop to eat their food or to drink water.
As they traveled the route, which often took many months, they would need safe places to sleep and places to eat along the way. Churches and villages that had accommodations to offer to the pilgrims began using the symbol of the scallop shell to indicate a welcome - sort of like a motel vacancy sign.
As a centuries-old symbol of welcome and of lodging and food, the scallop shell soon became incorporated as a popular motif in textile design, was used in flatware and dinnerware patterns and is even used in the mouldings of elegant French mansions. The picture below shows the scallop shell moulding in the corners of a dining room of a maison de maître in the South of France.