Cello inexpensive wood that has been blackened or "ebonized" to look like ebony, which is much harder and more expensive. Ebonised parts such as tuning pegs may crack or split, and the black surface of the fingerboard will eventually wear down to reveal the lighter wood underneath. Historically, cello strings had cores made out of catgut, which, despite its name is made from sheep or goat intestines which are dried out. Most modern strings used in the 2010s are wound with metallic materials like aluminum, titanium and chromium. Cellists may mix different types of strings on their instruments. The pitches of
Rubab (instrument) a membrane, covering the hollow bowl of the sound-chamber, upon which the bridge is positioned. It has three melody strings tuned in fourths, two or three drone strings and up to 15 sympathetic strings. The instrument is made from the trunk of a mulberry tree, the head from an animal skin such as goat, and the strings either gut (from the intestines of young goats, brought to the size of thread) or nylon. The "rubab" is known as "the lion of instruments" and is one of the two national instruments of Afghanistan (with the zerbaghali). Classical Afghan music often features