Large vase with lid

The word ivory is usually taken to mean elephant tusk, but can include the teeth of many different animals such as the hippopotamus, walrus, sperm whale, and wart hog. Antler and bone have also been used for similar purposes. The ivory of each species has a distinctive structure that can be used to identify the animal from which it comes. Some polished crosssection examples of various types are displayed here. The tusks of both African and Asian elephants have distinct intersecting, arching lines that can often be seen with the naked eye. These crosshatching lines (or "engine turning") are most evident in cross section and can easily be seen on the inside of this finely carved lid. Compare this structure with the cross section of elephant tusk. Note that the structure is more difficult to detect in elaborately carved areas. If the characteristic structures are not visible, it is occasionally not possible to determine the source of the ivory from which an object was carved.