A piece of armor plate that was to be used on another of Japan's "Yamato" class battleships
The Yamato was enormous. Looking like a scaled up "IOWA" class ship, it was huge, and fitted with 9x 18" guns and impressive armor, as you cna see here. This piece of armor was "liberated" from the Japanese docks after the war, and used at the Navy Yard to test the armotr penetration by their 16" shells, which handily passed thru the armor as you can see here. Massive spalling of the armor, with giant chips shattered off of the steel. Impressive.