Is it a bird? Is it a plane? No, it's a flying shark skin. In its never-ending quest to develop more aerodynamic, more fuel-efficient aircraft, the aviation industry believes the ocean's oldest predator, the shark, could hold the key to cutting energy consumption. Germany's biggest airline Lufthansa announced earlier this month that two of its Airbus A340-300 jets would take part in trials starting this summer to test the properties of shark skin in flight.