Perhaps the most well-known fossil material in the world, petrified wood is not wood at all but rather the fossilized remnants of trees from millions of years ago. Tree trunks, limbs, and branches that died under conditions that favor fossilization gradually become replaced with minerals until what remains is a replica of the original piece of wood consisting entirely of mineral material. Like the trees they capture the form of, each is unique and when cut vertically can reveal a cross section of the tree, sometimes including growth rings. Depending on the minerals present during fossilization, petrified wood can display an enormous variety of colors, textures and patterns. Each of these cut and polished slabs originates from Indonesia and is approximately 20-23 million years old.