Fish scale the surface, interacting only with the riblet tips, not causing any high-veloctiy flow in the valleys. Since this high velocity flow now only interacts with the riblet-tip, which is a very small surface area, the momentum transfer which causes drag is now much lower than before, thereby effectively reducing drag. Also, this reduces the cross-stream velocity fluctuations, which aids in momentum transfer too. The rough, sandpaper-like texture of shark and ray skin, coupled with its toughness, has led it to be valued as a source of rawhide leather, called shagreen. One of the many historical applications of shark shagreen was
The Shagreen Bone the "Wild Ass's Skin" turned into a "Bone"? One can answer like this, for example: how many years have passed "since then"? Anything that does not decompose ossifies and then petrifies. In the novel Vanière, the gardener of monsieur Raphael de Valanten, examines with surprise a shagreen he found in a well and says: "dry as wood and not greasy at all." Thus, the work illustrates the idea of ossification of any culture, including classical ballet. "The Shagreen Bone" is somehow the "reset" (rejection) of the culture of ballet. Subjected to the laws of ballet and summarizing the results of