Argonauta argo, also known as the greater argonaut, is a species of pelagic octopus belonging to the genus Argonauta. The female of the species, like all argonauts, creates a paper-thin eggcase that coils around the octopus much like the way a nautilus lives in its shell, hence the name paper nautilus. The Chinese name for this species translates as "white sea-horse's nest". A. argo was the first argonaut species to be described and is consequently the type species of the genus. A. argo is the largest species in the genus and also produces the largest eggcase. Live animals have a characteristic blue sheen on the first arm pair and around the eyes. The eggcase is characterised by two rows of small, sharp tubercles running along a narrow keel, smooth ribs across the walls of the shell, and a