The mollusks are a group of animals that is one of the oldest in existence. This groups of animals has two primary characteristics that make them easily distinguishable from the other animal groups, one of them being that they are unsegmented, and the other that they are bilaterally symmetrical. Being bilaterally symmetrical means that the left side and the right side of the body are perfect copies of one another, mirror images. Animals that are considered as mollusks are the snails, slugs, octopuses, squids, cuttlefish, shrimps etc.
