An anvil is a block with a hard surface on which another object is struck. The block is as massive as it is practical, because the higher the inertia of the anvil, the more efficiently it causes the energy of the striking tool to be transferred to the work piece. On a quality anvil the smiths hammer should rebound with almost as much energy as the smith puts into the downward stroke, ultimately making the smiths job easier and less physically strenuous. In most cases the anvil is used as a forging tool. Before the advent of modern welding technology, it was a primary tool of metal workers. The great majority of modern anvils are made of cast or forged steel (the latter is stronger) that has been heat treated. Inexpensive anvils have been made of cast iron and low quality steel, but are considered unsuitable for serious use as they deform and lack rebound when struck. Because anvils are very ancient tools and were at one time very commonplace, they have acquired symbolic meaning beyond their use as utilitarian objects. They have even found their way into popular culture including episodes of Looney Tunes, the name of a hardcore heavy metal band, and usage by artisanal blacksmiths as well as jewelers and metal smiths.