The middle layer, known as the prismatic layer, has a squamatic texture and the prismatic structure characteristic of Prismatoolithidae.
2.
The periostracum and prismatic layer are secreted by a marginal band of cells, so that the shell grows at its outer edge.
3.
In some dinosaur eggs, the prismatic layer exhibits squamatic ultrastructure, where the prismatic structure is obscured by a rough texture resembling lizard skin.
4.
The calcium carbonate layers in a shell are generally of two types : an outer, chalk-like prismatic layer and an inner pearly, lamellar or nacreous layer.
5.
The second layer is alternately called the prismatic layer, the columnar layer, the continuous layer, the crystalline layer, the palisade layer, or the single layer.
6.
"Triprismatoolithus " is notable for having three structural layers, The second layer, known as the prismatic layer, is made up of closely packed calcite crystals, and exhibits irregular squamatic texture.
7.
The periostracum is composed of a protein called conchin, and its function is to protect the prismatic layer from abrasion and dissolution by acids ( especially important in freshwater forms where the decay of leaf materials produces acids ).
8.
RT-PCR demonstrated that the transcript of aspein is expressed at the outer edge of the mantle, corresponding to the calcitic prismatic layer, but not at the inner part of the mantle, corresponding to the aragonitic nacreous layer.
9.
In the pearly mussels there is an inner iridescent layer of nacre ( mother-of-pearl ) composed of calcium carbonate, which is continuously secreted by the mantle; the prismatic layer, a middle layer of chalky white crystals of calcium carbonate in a protein matrix; and the periostracum, an outer pigmented layer resembling a skin.
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