title: Organic membranes determine the pattern of the columnar prismatic layer of mollusc shells.
abstract: The degree to which biological control is exercised compared to physical control of the organization of biogenic materials is a central theme in biomineralization. We show that the outlines of biogenic calcite domains with organic membranes are always of simple geometries, while without they are much more complex. Moreover, the mineral prisms enclosed within the organic membranes are frequently polycrystalline. In the prismatic layer of the mollusc shell, organic membranes display a dynamics in accordance with the von Neumann-Mullins and Lewis Laws for two-dimensional foam, emulsion and grain growth. Taken together with the facts that we found instances in which the crystals do not obey such laws, and that the same organic membrane pattern can be found even without the mineral infilling, our work indicates that it is the membranes, not the mineral prisms, that control the pattern, and the mineral enclosed within the organic membranes passively adjusts to the dynamics dictated by the latter.
authors.affiliation: Departamento de Estratigrafía y Paleontología, Universidad de Granada, 18071 Granada, Spain Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Armilla, 18100 Granada, Spain acheca@ugr.es.
authors.forename: Antonio G
authors.identifier: 0000-0001-7873-7545
authors.initials: AG
authors.lastname: Checa
authors.affiliation: Departamento de Estratigrafía y Paleontología, Universidad de Granada, 18071 Granada, Spain Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Armilla, 18100 Granada, Spain emacias@ugr.es.
authors.forename: Elena
authors.initials: E
authors.lastname: Macías-Sánchez
authors.affiliation: Department of Earth Sciences, Cambridge University, Cambridge CB2 3EQ, UK emh21@cam.ac.uk.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Harper
authors.affiliation: Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, 18071 Granada, Spain Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Armilla, 18100 Granada, Spain julyan.cartwright@csic.es.
authors.forename: Julyan H E
authors.identifier: 0000-0001-7392-0957
authors.initials: JH
authors.lastname: Cartwright
mesh_terms: D060105:Animal Shells / Q000033:anatomy & histology* / Q000737:chemistry*; D000818:Animals; D049872:Bivalvia / Q000033:anatomy & histology* / Q000737:chemistry / Q000502:physiology; D002119:Calcium Carbonate / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D013818:Thermogravimetry
chemical_list: D002119:Calcium Carbonate
keywords: biomineralization; mollusc; prismatic layer