Any of various chiefly marine gastropod molluscs constituting the prosobranch order Archaeogastropoda, which show several primitive characteristics and comprise many sea snails, limpets, abalones, and related forms.
These are now generally regarded as paraphyletic and recent classifications place them in various subclasses.
1950s; earliest use found in John Edward Morton (b. 1923). From archaeo- + gasteropod, after scientific Latin Archaeogastropoda, order name.