acritarch

From Ancient Greek ἄκριτος (ákritos, “doubtful, indistinguishable”) +‎ -arch.

• IPA^(key): /ˈækɹɪtɑː(ɹ)k/

acritarch (plural acritarchs)

1. (paleontology, palynology) Any small, non-acid-soluble (i.e. non-carbonate, non-siliceous) organic fossil that cannot be classified.
   • 2018, Mark Carnall, “Unidentifiable fossils: palaeontological problematica”, in The Guardian‎^[1]:

     Acritarchs represent some of the earliest evidence of life on Earth.

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