[Excerpt from a book on sailing traditions and scrimshaw]
Bone charms, a sailor's blessing, they say.
The carving itself is a practice from long back, passed from father to son, old man salt to greenhorn still getting his sea legs beneath him. In the old times, men cut into the tusks of ice seals and into the arm-long fangs of bears that roamed the isles north of Tyvia.
Once the whale trade began, the practitioners went to engraving the bones of these great beasts, rendering charms that sing in the night and grant some small boon to a man's vigor or defense against pregnancy.