Connecting the environment of the ancient past with the natural and cultural history of yesterday and today.



Featured Fossil


This page will feature fossils from all geological time periods. Each image will have

some background about the specimen, its age, where it was found, and a nugget

of interesting information. Not every specimen will be perfectly preserved -

but all are a marvel of the natural world!


Alga - former coral Prismostylus approximatum

Fossil Type:



Prismostylus approximatum (Ulrich)




Cincinnatian, Upper Ordovician


Madison, Jefferson Co., Indiana


Formally described as the odd tabulate coral Tetradium, it is now placed as a type of red algae. Click here to learn more. Prismostylus has a variety of forms, including massive mound shaped colonies. In cross-section the tubes have a four-leaf clover structure. Click here for another view. Anonymous collection.

Date Posted:

July 23, 2014


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Created April 12, 2012