Females of this unusual octopus species sequester themselves in thin,
translucent shells with which they drift across the open seas. Paper
nautiluses, also called argonauts, secrete the shells to serve as cases
for their eggs—but it has recently been discovered that they also
function as air-trapping ballast tanks, which allow the cephalopods to
hang effortlessly in the water column without sinking. This is the only
species known to use surface air bubbles to effectively control the
animals' ...
