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
Lampshades made from human skin lampshades and other items. In a 1970 episode of the first series of "Monty Python's Flying Circus" sketch "Mr. Hitler and the Minehead by-election", Adolf Hitler (played by John Cleese) says, "If he opens his big mouth again ... it's lampshade time!" In the 1973 London Weekend Television drama "The Death of Adolf Hitler", Doctor Karl Gebhardt (played by Ray McAnally) claims to Hitler (Frank Finlay) that the lampshade in his office in the Führerbunker is made of human skin. Hitler is disgusted and flies into a rage, violently throwing the lamp away, showing Hitler's cognitive dissonance between his personal