haʊˈɛvɚ, plˈɛktɹənˌoʊsɹəz ænd ˈʌðɚɹ ˈɜːli sˈɛfɐləpˌɑːdz kɹˈɛpt ɐlˈɔŋ ðə sˈiːfloːɹ ɪnstˈɛd ʌv swˈɪmɪŋ, æz ðɛɹ ʃˈɛlz kəntˈeɪnd ˈeɪ "bˈæləst" ʌv stˈoʊni dᵻpˈɑːzɪts ˌɔn wʌt ɪz θˈɔːt təbi ðɪ ˌʌndɚsˈaɪd, ænd hæd stɹˈaɪps ænd blˈɑːtʃᵻz ˌɔn wʌt ɪz θˈɔːt təbi ðɪ ˌʌpɚ sˈɜːfɪs.
However, Plectronoceras and other early cephalopods crept along the seafloor instead of swimming, as their shells contained a "ballast" of stony deposits on what is thought to be the underside, and had stripes and blotches on what is thought to be the upper surface.