Unusual Carboniferous Stromatoillite Nodule

Coming from Kansas, this Carboniferous-age stromatolites can be considered young when compared to some of its over 2 billion year old precursors. By the time it was formed, the cyanobacterial organisms and their stromatolitic reef systems were becoming quite restricted on earth, having retreated to environments less favorable to other marine life (including other microorganisms, algae and animals) with which they competed or from which they suffered predation.

Long believed to be a sponge, it acquired the name Somphospongia sp. While the resemblance is rather striking, it was later determined to be stromatolite.