Here are four pictures of the helmet Saburu Sakai wore on his fateful mission over Guadalcanal when he was wounded. The helmet, in the George Bush Gallery of the Pacific War at the Nimitz Museum , clearly shows the damage done by the offending projectile. The goggles are dented and the leather of the helmet is torn.
This helmet is from a pilot shot down by a US Navy fighter. The J-Pilot tried to shoot his US
Navy captors when they went to pick him up out of the sea, his pistol failed to fire and he was taken alive. This is a G.Bush Gallery item too.
This is from the case at the G. Bush Gallery/Nimitz that holds other relics of the shoot down of
Yamamoto. The metal fragment itself is unlabeled, but I assume it to be an actual piece from the wreck.
Click Image to enlarge