Any guesses? Some sort of textile equivalent of a grass skirt? An ancient example of a fidget toy? It’s actually pretty practical. Quipu: an ancient Incan data recording device consisting of variously colored ropes knotted in different patterns But what if . . . the data it stored was a secret message? I looked at this picture and saw a perfect tool for spies. I’m editing the first book in The Prophet Chronicles, and this device will be on the pages. This quipu (KEE-POO) doesn’t just keep a record of crop yields or tax payments. Hurgalan spies carry top-secret information embedded in the quipu’s knots from Ariel, the capital of…