Want to send a message to someone but keep a little bit of mystery? Invisible Ink lets you do just that. Here's how to use it ...

A 110-year-old lemon used by a German WW1 spy to send secret messages from Britain with invisible ink is going on display ... He pierced lemons with a pen nib to extract the juice and insert ...

But not all of the new features are easy to find. SEE ALSO: 12 hidden features in iOS 10 The ability to send messages with the new "invisible ink" feature, along with some of the other new effects ...

Muller used lemon juice as invisible ink to inform on British troop movements. A warm iron was passed over a letter to reveal the secret messages. The lemon was found in his overcoat when he was ...