Cystoids and Blastoids: Primitive Stalked Marine Animals (PA-10)
Fossil blastoids are found in the Silurian Osgood Shale in southeastern Indiana. Fossil cystoids have been collected from ancient Silurian reefs in northern and central Indiana and Mississippian rocks in south- central Indiana. Blastoids and cystoids lived in communities with crinoids, corals, brachiopods and byozoans.
Our Hoosier State Beneath Us: Paleontology