Brachiopods are among the most abundant animals in the North Vernon Limestone. One trilobite, called Phacops, is common in this formation. It can found flat or enrolled. Trilobites enrolled when they sensed danger. A storm or a shift in sea floor sediment might bury them.
Most Devonian trilobites have multi-faceted eyes similar to an insect's.
These creatures may have been the first organisms to see the world around them clearly and in color. The large fish in the background is Cladoselache, a primitive shark. The fossil fish bone fragments are black, but turn blue upon exposure to sunlight. They are most common where limestone rock changes to black shale. By exploring the fossil beds below the Interpretive Center and examining the diorama inside, it is possible to appreciate the wonders of fossils and the difficultly of interpreting their remains.