Microfossils of the Salem Limestone (DS-01)
It is composed of tiny fossils and small fossil fragments deposited in large sandbars in a shallow sea that covered Indiana about 300 million years ago. One of its most common fossils is the tiny shell of a single-celled animal called Endothyra baileyi. These shells were at first mistaken for small spherical particles called oolites, meaning petrified fish eggs, and the limestone was knows locally as oolite limestone.
Our Hoosier State Beneath Us: Dimension Stone