Gelatinous Siphon Sheath Templates the Starfruit-Shaped Aragonite Aggregate Growth

Figure 7

Schematic of the possible formation process of aragonite aggregates: (a) ACC formed on the surface of substrate; (b) ACC transformed into aragonite crystals by the β-chitin template; (c) aragonite crystals aggregate, orient, and attach to form an irregularly shaped structure (vertical view); (d, e) starfruit-shaped structure formed by adhered oriented crystals and continuous adhesion of ACC, as well as the transformation of ACC into aragonite crystals (vertical view); and (f) the starfruit-shaped structure develops gradually into a spindle-shaped structure (longitudinal view).