An oyster is a type of shellfish that lives in saltwater and is known for its hard, protective shell. Inside, oysters can produce a precious substance called pearl, which forms when an irritant gets trapped inside the shell. Oysters are not only fascinating creatures but also a popular delicacy enjoyed by many people around the world, often served raw on the half shell. These marine animals play an important role in their ecosystems. They help filter water, improving its quality by removing pollutants and excess nutrients. Additionally, oysters can form reefs, which provide habitat for various marine species, contributing to the overall health of coastal environments.