world war one - What's this 1917 shell casing, more exactly

I've been gifted this vase that is obviously made out of a large shell casing. It has 'MARZ 1917' stamped on the bottom, plus other less understandable markings: 'St', 'G', '36', 'HL 25'. I'm attac

Were there really piles of spent artillery shells littered across the battlefields of WW1? If so, what'd they do with them all after the Armistice? - Quora

Transport And Supply During The First World War

World war one bullets hi-res stock photography and images - Alamy

18-lbr. Shellcase Markings request - Arms and other weapons - The Great War (1914-1918) Forum

1917 Shell Casing - UK

1917 Shell Casing

Shell (projectile) - Wikipedia

WW1 artillery shell identification - Arms and other weapons - The Great War (1914-1918) Forum

Ww1 Shell Casings

Pair of WW1 British Brass Artillery Shells Dated 1917 For Sale at 1stDibs 1917 artillery shell, antique artillery shell for sale, ww1 shells for sale

German shell casing help please. - Arms and other weapons - The Great War (1914-1918) Forum

shell case dated 1917 - Arms and other weapons - The Great War (1914-1918) Forum

Ww1 shell hi-res stock photography and images - Alamy

1914 1918 Verdun Trench Art Shell From World War I