This question highlights the way that this novel not only is a gripping read in terms of plot, characterisation and themes, but also how it is so engaging in terms of its presentation of a culture and group that is so radically different from modern day perceptions of the world. The way in which cowries become a system of currency in this tribe indicates both their rarity but also man's instinctive economic interest, and there are a number of points in the novel when cowries are used in this way. One of these is when Okonkwo violates the Week of Peace by expressing anger towards his wife. As a result, he has to pay a punishment which is set by Ani, the priest of the earth goddess:

You will bring to the shrine of Ani tomorrow one she-goat, one hen, a length of cloth and a hundred cowries.

Cowries then were part of the economic life of this tribal group, and exchanged as part of the transfer of belongings that occurred during normal, everyday interactions between groups of people. Although the command of the priest represents the transfer of cowries as a punishment, the novel elsewhere testifes as to how their transfer results from other occasions as well, such as dowries and exchange of goods. This is one way that Okonkwo's tribe can be seen as being rather similar to today's world: an economic system is developed in both and accepted by all.