Sailor's Valentines, a maritime art thought to have originated in the early 1800's, are octagonal wooden boxes decorated with seashell mosaics and covered with glass. They were bought by sailors in the port of Barbados from 1830-1880 and given to their sweethearts when returning from long journeys at sea.
Valentine 21 (expanded view)

11" valentine, boy giving girl a rose, green urchin spines