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
Creatures of the Night completely absent from "Creatures of the Night", making it the heaviest album the group had made at that point. "I Still Love You", the only ballad on "Creatures of the Night", was still heavier and darker than any ballad Kiss had released in earlier years. Also contributing to the heavy sound was Carr's drumming style, which was similar to John Bonham's drumming than to Criss' jazz-influenced style. Some of the earliest pressings of the album mistakenly contained one full side of John Cougar's "American Fool". Both Kiss and Cougar were under the umbrella of Mercury Records at the time. "Creatures