Atomic structure and ultrastructure of the Murex troscheli shell

Area of Science:

• Biomineralization
• Materials Science
• Geology

Background:

• Gastropod shells exhibit complex hierarchical structures.
• Understanding shell ultrastructure informs biomimetic material design.

Purpose of the Study:

• To investigate the detailed structure of the Murex troscheli gastropod shell.
• To analyze the relationship between shell structure, organic content, and thermal properties.

Main Methods:

• High-resolution scanning and transmission electron microscopy (HREM).
• Synchrotron X-ray powder diffraction (SXRPD) with Rietveld refinement.
• Thermal gravimetric analysis (TGA).

Main Results:

• Anisotropic distortions in the orthorhombic aragonite unit cell were identified.
• Mild annealing (150–250 °C) relieved lattice distortions and reduced organic content.
• Shell ultrastructure revealed three hierarchical orders typical of crossed-lamellar layers.
• Third-order lamellae are heavily twinned, with organic-free boundaries.

Conclusions:

• The Murex troscheli shell exhibits unique structural features, including twinned lamellae.
• Thermal annealing affects shell ultrastructure by reducing organic matter and lattice distortions.
• Findings provide insights into gastropod shell formation and mechanical properties.