The bronze bell is in the shape of a flattened-out-temple-bell (temple bell itself appeared later in Japan), and the bronze bell is supposed to have had its prototype in the Korean Peninsula, but it developed uniquely in Japan.
銅鐸は後世の釣鐘を扁平に圧しつぶしたような器形で、その祖形は朝鮮半島にあったと推定されるが、日本で独自に発達をとげた銅器である。