paper nautilus

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A cephalopod mollusk (Argonauta argo) with eight tentacles, the female of which inhabits a paper-thin shell that later acts as an egg case. Also called argonaut.

Century Dictionary and Cyclopedia

1. n. The paper-sailor or argonaut. See Argonaut, Argonautidæ and nautilus.

Wiktionary

1. n. A pelagic octopus of genus Argonauta, found in warm seas, whose females produce a paper-thin egg case resembling a shell into which she deposits her eggs.

GNU Webster's 1913

1. n. (Zoöl.) See Argonauta.

WordNet 3.0

1. n. cephalopod mollusk of warm seas whose females have delicate papery spiral shells