AI overview
A shell is an artillery projectile that explodes when it hits its target or is triggered to detonate in the air. It matters because it's a fundamental weapon used in warfare that can cause significant damage and casualties over considerable distances.
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Article
Some sectioned shells from the First World War. From left to right: 90 mm shrapnel shell, 120 mm pig iron incendiary shell, 77/14 model – 75 mm high-explosive shell, model 16–75 mm shrapnel shell. US scientists with a full-scale cut-away model of the W48 155 millimeter nuclear artillery shell, a very small tactical nuclear weapon with an explosive yield equivalent to 72 tons of TNT (0.072 kiloton). It could be fired from any standard 155 mm (6.1 inch) howitzer (e.g., the M114 or M198). 155mm M107 projectiles, with fuzes fitted.
A shell, in a modern military context, is a projectile whose payload contains an explosive, incendiary, or other chemical filling. Originally it was called a bombshell, but "shell" has come to be unambiguous in a military context. A shell can hold a tracer.