amphibious phenomenon of cartoons, comics, motion pictures; “heroes in a half-shell” first appeared in comic books written by Peter Laid and Kevin Eastman (1983) as human-sized inhabitants of New York City sewers known for their martial-arts skill, passion for deep-dish pizza, California “surferspeak,” and Renaissance artists' names—Michelangelo, Raphael, Donatello, Leonardo; starting in 1986, toys and monthly comic books spurred animated television series, videos, breakfast cereal, many other products; live-action ‘Teenage Mutant Ninja Turtles' (1990) 2nd biggest movie debut in U.S. history, with revenues estimated eventually to total 100 million dollars.