WWI German Brooch - Made from Artillery Shell Band

Vintage WWI brooch made from an artillery shell band. It is carved 1914 1917 with a small iron cross and ribbon etched in the center.I am unsure if this piece was made by a soldier for a sweetheart during the war or a piece made by a veteran to wear himself after the war to commemorate his service (soldiers who were wounded by shrapnel, would turn the piece into something artistic to show what had happened). Either situation is plausible.It is in good condition, but it does show some wear. It measures about 1 1/4' by 1/2'.