The spire is a protruding part of the shell that includes all of the whorls except the largest and final whorl (known as the body whorl). It is usually more elongated than in other strombid snails, such as the closely related and larger goliath conch, "Lobatus goliath" that is endemic to Brazil. In "A. gigas", the glossy finish or glaze around the aperture of the adult shell is primarily in pale shades of pink. It may show a cream, peach or yellow colouration, but it can also sometimes be tinged with a deep magenta, shading almost to red. The periostracum, a layer of protein (conchiolin) that is the outermost part of the shell surface, is thin and a pale brown or tan colour.