The 2016 family animated film The Secret Life of Pets (streaming now on Peacock) follows a group of New York City pets and, as the title suggests, the secret lives they lead when their human companions are away. We can’t confirm (or deny) that animals get up to all sorts of hijinks when we’re not looking, but they do have some secrets that we’re only just unlocking. Those secrets apparently include the ability to glow in the dark, a process more officially known as fluorescence, according to a r