Kongo carvers produced wooden carvings (minkisi, singular: nkisi) in human form, which were used in rituals to solve problems or to gain wealth, and also in the form of animals, particularly the double-headed dog Kozo.
Among the Kongo wild animals are associated with the dead, who are buried away from villages, either in the forests or across rivers. Domesticated animals such as dogs live in villages but are used to hunt game in the forests. They are, therefore, considered as mediators between the worlds of the living and the dead.
Kozo's two heads and four eyes make him particularly potent in this role. Powerful medicines bound with resin or clay, a substance particularly associated with the dead, are placed on the animal's back; these empower the figure to act on behalf of the nganga or ritual specialist. To instruct the nkisi in a particular task, the nganga would drive an iron blade into the figure, with an accompanying invocation.