In Western mythology seven is widely regarded as a mystical number.
In certain parts of Africa seven is also a significant number.
A mask of the Guru (Côte d' Ivoire) has numerous scarifications (small flesh cuts that leave raised scars). There are sets of three scars and sets of four - being respectively male and female numbers. These sets of scarifications each, as a group, total seven.
This is clearly deliberate, for in the description of the mask it is stated that seven is the number that represents sexual completeness. Similarly our mask has elements of seven. The total eye, mouth and nose parts is seven. There are seven vertical bars within the headdress.