a coiled shell is made of one or more coils, each coil is called a whorl; the last one is the body whorl, the first ones are the embryonic whorl(s) or protoconch whorl(s). The shape of the coiling is expressed in a formula (W : X : Y : Z), the sizes are sometimes taken in a different way as shown in the illustrations.

Alternative forms for whorl : body whorl, embryonic whorls, whorls.