A shell is an aerial item that is fired into the sky. It generally consists of a fuse, a lift bag, and a paper ball filled with stars and burst media. The fuse lights the lift bag on the bottom of the shell propelling it into the sky. At the same time, an internal time fuse is triggered and at the right time the paper shell bursts with all of its stars lit. The type of stars contained inside the shell determines the effect the shell produces in the sky.