ammunition consisting of a cylindrical metal casing containing an explosive charge and a projectile; fired from a large gun

the material that forms the hard outer covering of many animals

hard outer covering or case of certain organisms such as arthropods and turtles

同义词：

carapace

cuticle

shield

the hard usually fibrous outer layer of some fruits especially nuts

the exterior covering of a bird's egg

同义词：

eggshell

a rigid covering that envelops an object

"the satellite is covered with a smooth shell of ice"

a very light narrow racing boat

同义词：

racing shell

the housing or outer covering of something

同义词：

case

casing

a metal sheathing of uniform thickness (such as the shield attached to an artillery piece to protect the gunners)

同义词：

plate

scale

the hard largely calcareous covering of a mollusc