"Paper thin" is a good description. Argonauta are known as "paper nautilus",
and A. hians is known as the "brown paper nautilus".  These are
cephalopods - the class of molluscs which includes octopus, squid,
cuttlefish, chambered nautilus, paper nautilus, and Spirula.  Unlike the
chambered nautilus, which has a true shell, Argonauta "shells" are actually
temporary brood chambers constructed by the female to protect the eggs.
Once they hatch, the "shell" is discarded.  I thought this took place at the
surface, but I am not certain about this.  Maybe someone else could comment
on this?  If so, the data you provided (trawled at 60 fathoms) would be
suspect.

Regards,
Paul M.