Beastplate of German tilting armour, of the first part of the 16th century. A very peculiar make which only has two specimens in existence (Ambras Collection and Museum of Artillery in Paris). When the center part of the breastplate was touched by the lance, the whole opened with a spring. The place to be touched was marked by a pierced heart.
Breast Plates in Ancient Weapons and Warfare
Ancient Images
Bible History Online