The maleo is a large, turkey-like bird with black and white feathers and a relatively bald head.  Perhaps the bird’s most distinctive feature is a large, round, bony protrusion on its skull, called a casque.  No one seems quite sure what this casque is for, though similar features in other birds work as a resonance chamber to make booming breeding calls.  In the maleo, the casque has been referred to as a football helmet, a walnut, or an engorged tick.