The standard American hand grenade of the war, the cast-iron Mk 2 got its enduring nickname 'pineapple' from the grooved, segmented surface meant to aid grip and fragmentation, and it was carried by virtually every US infantryman in every theatre.
Side view of a yellow Mk II-A1 grenade, dating from World War II. It is mounted with the M10A3 series fuse assembly.J-L Dubois · Public domain · sourceDepartment of Defense. Department of the Army. Office of the Deputy Chief of Staff for Operations. U.S. Army Audiovisual · Public domain · sourceAmerican rifle grenades from the Battle of the Bulge.(From Left to Right): M1 Grenade Adapter with Mk.2 Fragmentation Grenade, M22 Smoke Rifle Grenade with Impact fuze (unknown smoke color, possibly Green - munition was Sustructu · CC BY-SA 3.0 · source