Centreville High School (Fairfax County, Virginia) in the context of Bandshell

In theatre, a shell (also known as an acoustical shell, choral shell or bandshell) is a curved, hard surface designed to reflect sound towards an audience.

Often shells are designed to be removable, either rolling away on wheels or lifting into a flyspace. Shells are most commonly used for orchestras, bands and choirs, although they can also be used in any application that requires passive sound amplification. Shells are generally made of hard materials, because they are designed to absorb as little sound as possible.