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
Terror-Creatures from the Grave (Ennio Balbo). Other scenes included in the American cut involved a scene of a horse kicking a man to death. "Terror-Creatures from the Grave" was released in Italy on June 23, 1965, where it was distributed by Selecta. It grossed a total of 89 million Italian lire. The film was released on May 16, 1967 in the United States where it was distributed by Pacemaker Pictures. On the film's release abroad, Roberto Curti, author of "Italian Gothic Horror Films, 1957-1969", stated that "Terror-Creatures from the Grave" was "perhaps one of the most popular Italian horror films of the decade abroad."