A modern pilgrim?

The shell on this tombstone in Lake View Cemetery intrigues me.  A shell like this, specifically a scallop shell, is the pilgrimage symbol for Santiago de Compostela in Spain, where there is a shrine to the apostle St. James the Greater.  The shrine holds bones that are reputed to be those of the saint, also the patron saint of Spain, and has been a pilgrimage site for Christians since the 9th century.  Medieval pilgrims would wear a shell as a symbol of their journey, and such scallop shells are still available today.  Did Irvin make this journey and treasure it in such a way that a representation of it was to be on his grave marker?