Monday, October 26, 2020

102620d

 


 

Tiny fossil sponge, one of many embedded in a microbial reef. S = spongocoel, the hollow inside of the sponge; white arrow = needle-shaped spicules; M = fine-grained limestone mud matrix; F = fenestra, from the Latin for window, a relatively large void now filled with calcite cement crystals. Mississippian of North Alabama. Scale in the lower right.

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