| Abstract Scope |
Sheet nacre is a highly regular and periodic biogenic architecture composed of thin organic membranes and aragonitic layers, which are made of flat mesocrystalline platelets. Similar to classical crystal growth, nacre deposition is accompanied by incorporation of two-dimensional defects, such as dislocations and twinning, that are integral to its formation process. However, in contrast to a generic atomic-scale lattice, in sheet nacre, these defects occur on the mesoscale level. Specifically, twinning in aragonite is known to be responsible for the shape of nacre platelets and structural dislocations in the layered assembly are key to its morphogenesis. In the present work, we employ synchrotron-based nanotomographic imaging to visualize the nature and the dynamics of mesoscale dislocations in the nacre of the bivalve U. pictorum in 3D. By drawing an analogy to processes in classical materials science, we shed light on the role of structural dislocations and their interaction in nacre formation. |