What is Ivory Tusk

The ivory tusk in the story "The Headstrong Historian" is a symbol of the title that belongs to Nwamgba's husband. When Obierika dies his cousins take the ivory tusk that had belonged to him. When Anikwenwa gets old enough he demands the cousins give him the tusk back. Nwamgba is proud when the cousins do as Ankiwenwa asks.