pericalymma larva

The pericalymma larva is a stage in the life cycle of some primitive bivalve mollusks. This larva is characterized by a protective covering, or "test," made of cells that have cilia, which are tiny, hair-like structures used for movement. At the top of this test is a sensory plate of ciliated cells. After the juvenile mollusk grows from this test, it is shed, and the animal settles to develop into an adult.1

Mollusks themselves are a diverse phylum of invertebrates, with most species having separate sexes. Reproduction typically involves the release of eggs and sperm into the water for external fertilization, though internal fertilization also occurs in some groups. Many mollusks develop through free-swimming larval stages, such as the trochophore and veliger larvae, before metamorphosing into adults.1