Burglars in medieval Cairo would sometimes send a turtle with a lit candle on its shell into the house they were planning to rob. If someone was home, they'd cry out in amazement when they saw the turtle, scaring off the burglars. Otherwise, the robbery could go ahead. pic.twitter.com/qVkOpd4XRp— Elias Muhanna (@QifaNabki) December 7, 2018
The year is—let us say—1170, and you are the leader of a city watch in medieval Persia. Patrolling the dangerous alleyways in the small hours of the morning, you and your men chance upon two or three shady-looking characters loitering outside the home of a wealthy merchant. Suspecting that you have stumbled across a gang of housebreakers, you order them searched. From various hidden pockets in the suspects’ robes, your men produce a candle, a crowbar, stale bread, an iron spike, a drill, a bag of sand—and a live tortoise.
The reptile is, of course, the clincher. There are a hundred and one reasons why an honest man might be carrying a crowbar and a drill at three in the morning, but only a gang of experienced burglars would be abroad at such an hour equipped with a tortoise.