An approximately 3 foot by 3 foot section of rock, this slab boasts of 31 different species of animals (and many more individuals). It was purchased from Indiana fossil preparator Tom Witherspoon who collects on his property in Crawfordsville. The most common organism represented is an animal called a crinoid. Crinoids, commonly called sea lilies, belong to the Phylum Echinodermata and are related to such animals as starfish and sand dollars. Crinoids, although still alive today, were much more diverse in the past.

Western Indiana, near Crawfordsville (Montgomery County), has some of the most outstanding crinoid deposits in the world. These 350 million year old rocks were deposited when Indiana was on the edge of a sea. Crinoids, along with other types of organisms, lived on a delta (commonly referred to as the Borden Delta), much like today’s Mississippi River Delta. Inland storms would wash loads of sediment into the river and out onto the delta, instantly smothering-and preserving-intricate animal communities.

The Indiana State Museum has an excellent collection of professionally prepared fossils from the Borden Delta. Many of these are on display in the Ancient Seas Gallery. While individual fossils are very important, a preserved piece of the delta floor, showing how animals lived and died together, contains a very special story. For example, a large crinoid in the center of the slab has a rider-a starfish is nestled into its crown, feeding off of the crinoid’s waste.