Composite material in the sea urchin Cidaris rugosa: Ordered and disordered micrometre-scale bicontinuous geometries
Date
2024
Authors
Jessop, Anna-Lee
Millsteed, Allan J.
Kirkensgaard, Jacob Judas Kain
Shaw, Jeremy
Clode, Peta L.
Schroeder-Turk, Gerd
Journal Title
Journal ISSN
Volume Title
Publisher
Royal Society Publishing
Abstract
The sponge-like biomineralized calcite materials found in echinoderm skeletons are of interest in terms of both structure formation and biological function. Despite their crystalline atomic structure, they exhibit curved interfaces that have been related to known triply periodic minimal surfaces. Here, we investigate the endoskeleton of the sea urchin Cidaris rugosa that has long been known to form a microstructure related to the Primitive surface. Using X-ray tomography, we find that the endoskeleton is organized as a composite material consisting of domains of bicontinuous microstructures with different structural properties. We describe, for the first time, the co-occurrence of ordered single Primitive and single Diamond structures and of a disordered structure within a single skeletal plate. We show that these structures can be distinguished by structural properties including solid volume fraction, trabeculae width and, to a lesser extent, interface area and mean curvature. In doing so, we present a robust method that extracts interface areas and curvature integrals from voxelized datasets using the Steiner polynomial for parallel body volumes. We discuss these very large-scale bicontinuous structures in the context of their function, formation and evolution.
Description
Keywords
calcite, biomineralization, diamond, calciumcarbonate, curvature
Citation
Collections
Source
Journal of the Royal Society Interface
Type
Journal article
Book Title
Entity type
Access Statement
Open Access
License Rights
Creative Commons Attribution License