The maintenance of the integrity of the body by land-dwelling organisms in the face of the gravitational pull of the planet requires a support structure. For small organisms such as snails or insects mere muscular mass or an exoskeleton are enough, but larger and more massive organisms depend on the support structure that we call the skeleton. The interplay between the skeleton and its joints and ligaments with the muscles and the nerves also makes movement possible. The skeleton is composed of a matrix of crystals of calcium and potassium organized around fibers of a protein called collagen. But far from bone being an inert substance, it is constantly being made and degraded by specialized cells, and certain areas of some bones are actively involved in the production of red blood cells.
Apart from its biological usefulness, bone has been used by mankind throughout the ages as a material to generate tools ranging from weapons to combs, needles, sickles, and even musical instruments. Also noteworthy is the carving of bones to generate ornaments used in ceremonies, rituals, religion, and even art. In the majority of cases the bones used in these tools or ornaments are those of animals. However, sometimes the bones used are from human beings.
One of the most extreme examples of human bone art is the Sedlec Ossuary which is a small chapel located in the town of Kutna Hora in the Czech Republic. The Sedlec Ossuary contains the bones of 40,000 human beings arranged in various ornamental formations ranging from a chandelier to a coat of arms. This is the work of a woodcarver called František Rint. When the local cemetery got too full during the Middle Ages the bones would be moved from the graves to the basement of the chapel to make room to inter more people, and the bones accumulated for centuries. In 1870 Mr. Rint was appointed to put the bones in order, and he decided to make what is shown in the video below.