Lobster is in fact considered to be a shellfish, though most people have misconceptions at what this actually means. Shellfish are not actually a type of fish but rather animals that happen to live in the water. There are a number of different types of shellfish, including crustaceans which are what classification lobsters fall under.
Some of the different species of shellfish includes mollusks, echinoderms, and crustaceans. Lobsters are considered to be very highly-prized seafood and have a lot of nutritional value when it is eaten on a regular basis. Clawed lobsters are the most common kind in the culinary world, though some of their closest relatives include crayfish and reef lobsters.