Figures and data
![](https://prod--epp.elifesciences.org/iiif/2/91568%2Fv1%2Fcontent%2F560476v1_fig1.tif/full/max/0/default.jpg)
Specimens of miliolid foraminifera, identified as Pseudolachlanella eburnea (d’Orbigny), used for experimental studies. (A, B) SEM, (C, D) transmitted light microscope, and (E, F) stereomicroscope images; white arrows show the outer organic sheath of a new chamber during its gradual calcification expressed by its milky, opaque appearance; black arrows show a small mass of cytoplasm extruded from the aperture of exiting the chamber; green arrows show endosymbiotic algae.
![](https://prod--epp.elifesciences.org/iiif/2/91568%2Fv1%2Fcontent%2F560476v1_fig2.tif/full/max/0/default.jpg)
Fluorescence images of living P. eburnea conducted by Laser Scanning Microscopy. A-Cell impermeable Calcein (cyan) indicating endocytotic seawater vesicles, see Movie 1. B - FM1-43 membrane dye indicating endocytotic vesicles (red), see Movie 2. C, D, E - LysoGlow84 indicating acidic vesicles (navy blue), autofluorescence of chloroplasts (green), and Mg-ACC pools (red), see Movies 3 and 4, (note the overlap of ACC and acidic vesicles is marked in lilac).
![](https://prod--epp.elifesciences.org/iiif/2/91568%2Fv1%2Fcontent%2F560476v1_fig3.tif/full/max/0/default.jpg)
SEM images of the major steps of the formation of P. eburnea shell-building components. Test cross-section showing: (A, B) carbonate nanograins within organic matrix, (C, D) nanograins merging into needle-like mesocrystals, (E) fully developed needle-shaped elements; pn –nanograins partly transformed to short needles.
![](https://prod--epp.elifesciences.org/iiif/2/91568%2Fv1%2Fcontent%2F560476v1_fig4.tif/full/max/0/default.jpg)
SEM images showing successive stages of new chamber formation in P. eburnea. (A) outer organic sheath, (B) mineralized outer organic sheath, (C) calcite nanograins within a gel-like organic matrix, (D) needle-shaped mesocrystal growth, (E) needle-like calcite building elements,(F) nanogranular intrados.
![](https://prod--epp.elifesciences.org/iiif/2/91568%2Fv1%2Fcontent%2F560476v1_fig5.tif/full/max/0/default.jpg)
Simplified model of porcelaneous wall construction based on foraminifer P. eburnea.
![](https://prod--epp.elifesciences.org/iiif/2/91568%2Fv1%2Fcontent%2F560476v1_tbl1.tif/full/max/0/default.jpg)