Looks like a Big Bertha shell [1]. Those larger shells were fired by special-purpose guns built in very small numbers (only 12 Berthas were ever built), used to

Looks like a Big Bertha shell [1]. Those larger shells were fired by special-purpose guns built in very small numbers (only 12 Berthas were ever built), used to break sieges or against particularly strong front-line fortifications - for example, Big Bertha was first used in action against the Liege fortifications during the drive through Belgium. An even taller (but lighter) shell was fired by the Long Max [2] converted battleship guns. The majority of the bombardment was carried out by 75-85mm guns, like for example [3]. Their shells were about half the caliber, and a quarter the mass, of modern 155mm howitzer ammunition, but still twice the mass of modern light infantry mortar shells. [1] https://en.wikipedia.org/wiki/Big_Bertha_(howitzer) https://en.wikipedia.org/wiki/Big_Bertha_(howitzer) [2] https://en.wikipedia.org/wiki/38_cm_SK_L/45_%22Max%22 https://en.wikipedia.org/wiki/38_cm_SK_L/45_%22Max%22 [3] https://en.wikipedia.org/wiki/Ordnance_QF_18-pounder https://en.wikipedia.org/wiki/Ordnance_QF_18-pounder