One of the more unusual types of African art is 'currency.' Currency appears in a wide variety of shapes and forms, usually made of iron and copper, the metals most valued in this area of the world. African currency is not used like paper currency, although it does represents wealth and an abundant lifestyle. Commonly, it is given as a bride price, the opposite of a dowry. Whereas a bride brings a dowry to a marriage; currency is given to the bride's family by the groom to compensate them for the loss of their daughter. The currency itself has a simple, important meaning: we all exist, thrive, and can achieve common goals through co-operation and contribution. Among tribal cultures in Africa, currency could also be used for major purchases such as land or animals, or to signify a transfer of wealth at major events, such as birth, coming of age, marriage, or death. Most African currency forms were developed from traditional metal objects that were already in use such as weapons, tools, bracelets and anklets. While some continued to be functional for work or decorative purposes, most evolved into "pure" currency, deliberately unusable except as objects recognized, prized, and accepted as payment.