Among the many instruments collected by the German-Argentinian composer Mauricio Kagel are two frog clickers, a squeaky cat, and ten clockwork animals. Such children’s toys were a source of inspiration for Kagel’s music dramas. He recorded the noises made by everyday objects and so broadened the range of classical instruments. Croaking frogs were among the stars at the 1971 premiere of Kagel’s work “Staatstheater” at Hamburg State Opera.