Gojira's appearance has changed over the years, but many of his characteristics have remained constant. One characteristic that has remained stable is his roar. It was first created by Japanese composer Akira Ifukube by rubbing a resin glove over the strings of a contrabass. Other characteristics that have remained constant across all the Japanese films have been: Gojira being depicted as a gigantic dinosaur with rough, bumpy charcoal grey scales, a long powerful tail, and jagged, bone colored dorsal plates. Although his origins vary somewhat from film to film, he is always described as a prehistoric creature, who first appeared and attacked Japan at the beginning of the Atomic Age. In particular, mutation due to atomic radiation is presented as an explanation for his great size and strange powers.