As Netflix cracks down on password sharing around the world - something it once encouraged - we wondered why people like to share passwords to other things, such as phones, email accounts and logins. Passwords and encryption exist as ways of protecting us from hostile agents in most aspects of life. But timing is everything. Nature has been doing it for years of course. But climate change is upsetting some of the ecological match-ups of locks and keys, migration and feeding that have evolved over the millennia. We hear how the shifting patterns of weather and food availability is affecting cuckoos in Europe and India. Another aspect of natural subterfuge is camouflage. Whilst physicists have been trying to make optical invisibility cloaks from ingenious new "metamaterials", Marc Holderied and team have been looking at how certain moths have used metamaterial properties in the structure of their wings to effectively hide from bats. They are acoustically invisible. Could similar materials be manufactured to make, for example, sound-proof wallpaper? Also, we hear how India's Chandrayaan-3 moon mission - due to land on 23 August this year - is exciting millions of people. Presenter: Marnie Chesterton Producer: Alex Mansfield, with Margaret Sessa-Hawkins, Ben Motley and Sophie Ormiston