Koopa Troopas, or just simply Koopas, known in Japan as Nokonoko, are a fictional race of turtle or tortoise-like creatures from the Mario series, as well as its sister Yoshi series. Although the term 'Koopa' is a blanket term for the entire species of anthropomorphic turtles in the series, to which creatures such as Lakitu, Hammer Bros. and even Bowser belong, the term is often used to refer colloquially to this particular enemy. They are based on the kappa, a mythical creature from Japanese folklore. First appearing in the 1983 arcade game, Mario Bros., in which they were known as Shellcreepers, they are among the oldest recurring enemies in the series, and have appeared in some form in all of the main games, and most of the spin-off games. When defeated, Koopas may flee from or retreat inside their shells, which can then usually be used as weapons. Koopa shells are a recurring weapon in the series, particularly popularized in the Mario Kart series, in which they can be fired as projectiles against other racers.