A concha, or shell, is the hard, protective outer covering of certain marine animals, primarily mollusks like snails, clams, and oysters. These shells are made of calcium carbonate and serve as a defense against predators and environmental hazards. They come in various shapes, sizes, and colors, often reflecting the habitat and lifestyle of the creature inside. Conchas can be found on beaches around the world and are often collected for their beauty. They play a vital role in the ecosystem, providing habitat for marine life and contributing to the formation of beach sand as they break down over time.