The argonaut constructs its shell via physical self-organization and coordinated cell sensorial activity. (A. Checa et al.)_Dataset.

The shell of the cephalopod Argonauta consists of two layers of fibers that elongate perpendicular to the shell surfaces. Fibers have a calcitic core sheathed by extremely thin organic membranes, which form a polygonal network in cross-section. During growth, fibers with small cross-sectional areas tend to shrink, whereas those with large sections tend to widen, i.e. they follow the von Neumann-Mullins law. We hypothesize that fibers evolve as an emulsion between the fluid precursors of both the mineral and organic phases. In addition, when polygons reach big cross-sectional areas, they become subdivided by new membranes. To interpret this partitioning process we infer that the living cells from the mineralizing tissue are able to ‘locate’ and subdivide particularly large polygons. To do this, living cells must perform contact recognition and subsequent secretion at sub-micron scale. Accordingly, the fabrication of the argonaut shell proceeds by physical self-organization together with direct cellular activity