The gastropods (Lower Cambrian to Recent) are a group of univalve molluscs which typically have a spirally-coiled shell, although this is lost in some taxa, such as terrestrial slugs and marine sea slugs. The gastropods are highly successful, having invaded a range of marine (both benthic and planktic), freshwater and terrestrial environments, and having adapted their shell to a range of functions. Living and fossil gastropods are widespread and diverse, although constrained by living in a conical calcareous tube that maintains its overall form by growing in a spiral reminiscent of a corkscrew (Figs 1-4).
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