haʊˈɛvɚ, ðə hˈɛlʃənˌɛlɪdz, wˌɪtʃ fˈɜːst ɐpˈɪɹ ˌoʊvɚɹ ɪn ˈɜːli kˈæmbɹiən ɹˈɑːks fɹʌm saɪbˈiəɹɪə ænd tʃˈaɪnə, ɑːɹ θˈɔːt təbi ˈɜːli mˈɑːlʌsks wɪð ɹˈæðɚ snˈeɪllˈaɪk ʃˈɛlz.
However, the Helcionellids, which first appear over  in Early Cambrian rocks from Siberia and China, are thought to be early molluscs with rather snail-like shells.