A nkisi can reside in a statue or some other object, such as a shell, gourd, pot, a bundle of fibres, or a small box. Of these, the power figures are the best known, because of their particular appeal to European collectors. A nkisi’s help can be requested to offer protection from disease or some other calamity, punish criminals, or validate an agreement or an alliance. The ritual specialist or nganga brings a nkisi to life by attaching an empowering substance (bilongo) to it. Bilongo entices a spirit to come down from the heavens and to take up residence in the figure. If these magical substances fall out of the nkisi, it loses its powers. Bilongo often contains clay, white and red earth, resin, small bones, and seeds.