Just like the shell of a clam, a pearl is composed of calcium carbonate (mainly aragonite or a mixture of aragonite and calcite). in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes, known as baroque pearls, can occur.
Rimula is a genus of fungi in the Helotiales order. The relationship of this taxon to other taxa within the order is unknown (incertae sedis), and it has not yet been placed with certainty into any family. ^ Lumbsch TH, Huhndorf SM. (December 2007). Outline of Ascomycota â 2007.
The blastula is an early stage of embryonic development in animals. It is also called blastosphere. It is produced by cleavage of a fertilized ovum and consists of a spherical layer of around 128 cells surrounding a central fluid-filled cavity called the blastocoel.The blastula follows the morula and precedes the gastrula in the developmental sequence.Whereas, a gastrula is a phase early in the development of animal embryos, during which the morphology of the embryo is dramatically restructured by cell migration.eport Abuse. gastrula-An embryo at the stage following the blastula, consisting of a hollow, two-layered sac of ectoderm and endoderm surrounding an archenteron that communicates with the exterior through the blastopore.