Anaspidea

Anaspidea is a suborder of marine snails that belongs to the order Patellogastropoda. The name Anaspidea is derived from the Greek words "ana," meaning "without," and "spidē," meaning " shell." This suborder consists of about 30 species of snails, commonly known as abalone, earwigs, and pearls.

The Anaspidea snails are characterized by their lack of an external operculum, which is a protective plate that some snail species use to seal their shells when they are not using their foot. The shells of these snails are not typically used as a defense mechanism. They are also known for their lack of an umbone, a small projection found on the left side of the shell in many other snail species. Anaspidea snails typically live in shallow waters and can be found in tropical and subtropical oceans around the world.

These snails have a single large shell that grows throughout their lives, and it is used for protection and fertilization of eggs. Some species of Anaspidea snails have marine pearling oyster-like shells that are highly valued for their beauty and durability. The Anaspidea snails are herbivores and use their radula to scrape and grind their algal and plant food.

Biologists have found a loose correlation between the Anaspidea snails and the plant-eating habits of their ancestor. The shells of these snails contain layers of nacre, which is made of crystalline calcium carbonate covered in shimmering organic matrix material.