Microfossils

thumbnail|300px| Pine [[pollen under the microscope]] thumb|300px| A late Silurian [[sporangium bearing trilete spores. Such spores provide the earliest evidence of life on land. Green: A spore tetrad. Blue: A spore bearing a trilete mark – the Y-shaped scar. The spores are about 30–35 μm across.]]

soft diatomite variety

thumb|upright=1.1|Coccolithophore cells are covered with protective calcified (chalk) scales called coccoliths

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microscopic fossils

Cryptospores are microscopic fossilized spores produced by embryophytes (land plants). They first appear in the fossil record during the middle of the Cambrian period, as the oldest fossil evidence for the colonization of land by plants. A similar (though broader) category is miospores, a term generally used for spores smaller than 200 μm. Both cryptospores and miospores are types of palynomorphs.

thumb|right|An Ordovician scolecodont from Estonia