Phosphatic shell plate of the barnacle Ibla (Cirripedia): a bone-like structure.

The carbonate apatite crystals and the segmented structure of the shell plates of the barnacles in the genus Ibla distinguish them from the shell plates of all other barnacles, which are coherent calcitic structures. A detailed study of the hierarchical organization of one of the two shell plate types, the tergum, reveals a remarkably complex structure. Cylinders composed of a chitin-protein complex and nodes of plate-shaped crystals constitute the basic building blocks.

Transformation of amorphous calcium phosphate to crystalline dahillite in the radular teeth of chitons.

A comparison of infrared spectra from individual teeth along the radula of a chiton (Polyplacophora, Mollusca) shows that the first-formed calcium phosphate mineral is amorphous. Over a period of weeks the mineral transforms to dahllite. The c axes of the dahllite crystals are aligned approximately perpendicular to the tooth surface.

Mössbauer spectroscopy of iron-containing dermal granules from Molpadia intermedia.

Dermal granules containing hydrous ferric oxide cores from Molpadia intermedia were studied by Mössbauer spectroscopy from 1.5 to 300 K and in magnetic fields up to 80 kOersted at 4.2 K.

Minerals formed by organisms.

Organisms are capable of forming a diverse array of minerals, some of which cannot be formed inorganically in the biosphere. The initial precipitates may differ from the form in which they are finally stabilized, or during development of the organism one mineral may substitute for another. Biogenic minerals commonly have attributes which distinguish them from their inorganic counterparts.

Evolutionary prerequisites for early Phanerozoic calcareous skeletons.

This paper develops the concept that the dramatic appearance of calcareous skeletons in the Lower Cambrian is directly related to the origin of refined mechanisms of intracellular modulation of calcium ion concentration. An homologous family of calcium modulated proteins has recently been discovered. These proteins contain "EF hands", involved in the maintenance of low concentrations of intracellular calcium and the informational use of calcium ion flow (Kretsinger, 1977).