Shark skin. Coloured scanning electron micrograph (SEM) of scales on the skin of a shark. These sharply pointed placoid scales, also known as dermal teeth or denticles, disrupt turbulence over the skin, considerably reducing the drag on the fish as it swims. The tip of each scale is made of dentine overlaid with dental enamel. The lower part of each scale, which anchors it into the skin, is made of bone. This design has been investigated by engineers for use on the surfaces of aircraft and boats. Magnification: x33 when printed 10 centimetres wide.