What is the purpose of the egwugwu in Things Fall Apart?

The egwugwu are ancestral spirits of the clan. It is not known how many there are specifically. In tribal courts of Umuofia, there are 9 egwugwu, one representing each village.

A notable egwugwu is the Mother of Spirits, who makes an appearance after one of her sons is killed. Another is Ajofia, the leading egwugwu of Umuofia.