Ivory is a term for dentine, which constitutes the bulk of the teeth and tusks of animals such as elephants, when used as a material for art or manufacturing. Ivory is little used today, but has been important since ancient times for making a range of items, from ivory carvings to false teeth, fans, dominoes, joint tubes, piano keys and billiard balls. Elephant ivory has been the most important source, but ivory from many species including the hippopotamus, walrus, mammoth and narwhal has been used. The word ultimately derives from the Ancient Egyptian 璽b, 璽bu 'elephant'.