Short, J. W., 1989. How Shells are Formed. Queensland Museum Information Sheet.

Molluscs are soft-bodied, non-segmented invertebrate animals. To provide defence against predators and to minimise desiccation in terrestrial and intertidal environments, most molluscs produce a hard protective shell. Molluscs lacking a shell or with the shell located internally, rely on other defence mechanisms, such as cryptic colouration, unpalatable flavour, or the ejection of a cloud of ink.