<p>Stromatolites (cut &amp; polished slice) from the Precambrian of Montana (public display, Museum of the Rockies, Bozeman, Montana, USA).
</p><p>Stratigraphy: Snowslip Formation, Belt Supergroup, Mesoproterozoic, ~1.44 Ga.
</p><p>Locality: Glacier National Park, northwestern Montana, USA.
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<hr><p>Stromatolites are large, layered structures built up by mats of cyanobacteria.  Stromatolites vary in appearance, ranging from slightly wrinkled horizontal laminations in sedimentary rocks to low mounds to prominent mounds to columnar structures and other forms.
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Stromatolites are most common in the Proterozoic fossil record.  They are scarce today, but famous modern examples occur at Shark Bay, Western Australia.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/47445767@N05">James St. John</a>
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<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/jsjgeology/15015808670/">Stromatolites (Snowslip Formation, Belt Supergroup, Mesoproterozoic, 1.44 Ga; Glacier National Park, Montana, USA) 3</a>