05-29-2014 08:27 PM
Hi and welcome to the forum, I think you have an M40 (possibly M35, hard to tell) HEER helmet ,not KRIEGSMARINE, that has had the vent holes "plugged". That was maybe done post war to turn the helmet into a bucket/flowerpot/cooking pot etc. As for the large fracture, it could be from a "pot shot" or down to frozen water expanding inside the shell rather than a missile strike. Leon.
"Always do sober what you said you'd do drunk. That will teach you to keep your mouth shut." Ernest Hemingway