Check out this link at Harvard for more information about this creature.
The Louisville Fossils site also has an entry.

These creatures can might also be referred to as Paraconularia. You can find some more images of the Conularia on the KYANA Geological Society website:
http://www.kyanageo.org/Fossils/mississippian/other/Conularid_Coral_Ridge1.jpg
http://www.kyanageo.org/Fossils/mississippian/other/Conularid_in_nodule_Coral_Ridge.jpg
http://www.kyanageo.org/Fossils/mississippian/Corals/conularia.jpg
This link shows a nice specimen from Missouri.