ðɪ ˌʌpɚ ænd lˈoʊɚ sˈɜːfɪsᵻz ʌvðə fˈɑːsəlz hæv ɐ dɪstˈɪŋkt ˌɛlɪmˈɛntəl kˌɑːmpəzˈɪʃən ðæt ɹᵻzˈɛmbəlz ðæt ʌv fˈɑːsəlˌaɪzd bˌaɪoʊfˈɪlmz.
The upper and lower surfaces of the fossils have a distinct elemental composition that resembles that of fossilized biofilms.