Ivory, the hard substance of which elephant tusks are composed, is highly sought for the carving of ornamental objects. Most ivory is obtained from the tusks of African elephants, but other sources include the tusks of walruses and the fossilized tusks of prehistoric elephants and mammoths found in the northern glacial regions of the world. Although importation of ivory has been banned in many countries due to the fact that many of the species from which it is obtained are now endangered, the ivory trade was once a widespread and profitable venture.