aragonitic

The aragonitic composition of the shell makes it very sensitive to dissolution.

The internal layers of the shell are aragonitic and nacreous, in some species completely so.

Their aragonitic shells are not prone to fossilisation.

They were probably originally aragonitic.

Analysis of the skeleton of Coelosimilia does not seem to support development from aragonitic compounds.

The shell itself is aragonitic, consisting mainly of a prismatic layer, lined with nacre.

It consists of transverse bundles of aragonitic needles and protects the polyps.

Several serpulids have aragonitic tubes.

The fossils are hollow cones with porous walls that had an originally fibrous aragonitic mineralogy.

However, there are some unusual examples of well preserved aragonitic rugose corals in the late Permian.

The mineralogic composition of carbonate platforms may be either calcitic or aragonitic.

All chitons bear a row of aragonitic shells, although in some species they are reduced or covered by the girdle tissue.

They differ from most bivalves by having shells completely made up of calcite, but with internal muscle scars of aragonitic composition.

Some sabellids and cirratulids can secrete aragonitic tubes.

It rarely happens to soft tissue organisms and aragonitic fossils are more susceptible to it than calcite fossils.

They probably start life as amorphous calcium carbonate, which the organic matrix coaxes into an aragonitic habit as the spines mature.

Perlucin encourages carbonate deposition, and is found at the interface of the chitinous and aragonitic layer in some shells.

Brain cartilage is observed in some specimens, as well as a pair of aragonitic statoliths which helped the animal determine horizontal orientation when swimming.

Aragonite compensation depth (hence ACD) describes the same behaviour in reference to aragonitic carbonates.

Magnesium is a component of aragonite, and an abundance of the element is necessary for the development of aragonitic structure-building organisms.

The calcareous - probably aragonitic - shells have a cover (operculum) and two curved supports known as helens, all of which grew by marginal accretion.

Limacina helicina seems to be relatively more resilient to elevated concentration of carbon dioxide (CO) than other aragonitic organisms such as corals.

The phragmocone of Belemnotheutis had about 50 chambers that were originally aragonitic, though they are usually replaced by calcium phosphate during the process of fossilization.

However the low stability of their aragonitic shells means that few end up being preserved in sediments, these being in shallower waters of the tropical oceans.

The aragonitic shells of scaphopods are conical and curved in a planispiral way, and they are usually whitish in color.