According to Wikipedia, muesli appeared on our tables thanks to the Swiss doctor Maximilian Bircher-Benner, who invented this wonderful dish for his patients back in 1900. And only sixty years later, when Europe there was interest in healthy eating and low-calorie foods, muesli gained popularity.
Crunchies are grain muesli baked at low temperatures. The name ‘crunch’ probably comes from the English word crunch (crunching sound).