Leonardo da Vinci’s armored vehicle design was shaped like a turtle shell.
Leonardo drew the fighting vehicle in the late fifteenth century as a covered, conical machine with sloping armor. Its broad shell-like exterior was intended to deflect projectiles, while a group of cannons projected through openings around the perimeter. The vehicle was meant to move across a battlefield and provide protection for the soldiers operating the weapons.
The design is often called Leonardo’s tank, although it was not a modern tank. It had no engine, suspension, tracks, or practical steering system. Leonardo’s original drawing also appears to contain a gearing problem that would prevent the vehicle from moving as shown. Some historians have suggested that the error may have been deliberate, because Leonardo sometimes protected military designs from unauthorized use.
The turtle comparison describes the vehicle’s protective form, not an actual biological mechanism. Its concept combines armor, artillery, and mobility in one machine, making it a notable early ancestor of later armored fighting vehicles even though it was never known to have been built in Leonardo’s lifetime.