Fig. 12
From: Siphonal zone structure in the cuttlebone of Sepia officinalis
Spirula. Beach-collected shell; Cuba. Median shell section through tubular siphuncle showing slit-like permeable zone filled with spherulitic-prismatic deposits of pillar zone between two retrochoanitic septal necks. Scale bar is 500 µm. rsn1 and rsn2 two neighbouring retrochoanitic septal necks, sp slit-like permeable zone between two septal necks filled with spherulitic-prismatic deposits of pillar zone