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 its development, the work demonstrates the absurdity of ballet and its stagnant forms. The composer seems to rise from the orchestra pit and throw bones in the face of the audience, that is to say, ballet clichés: grand pas, fouettés, variations, adagios. Yet the result is a beautiful romantic ballet, showed twice: firstly the ballet as such, with its meaningless joy and conventional character, and secondly with the author's attitude. This was one of the reasons, among others, for changing the title and replacing the "skin" with a "bone." The Shagreen Bone The Shagreen Bone (, ) Op. 37-38 (1990)