This specimen is probably Wilkingia. But it could also be Phestia. I compared photos from a quick web search of each and I found examples of Wilkingia to be far more comparable. Wilkingia lived from the Carboniferous until the Permian periods of time. This particular specimen is from eroded matrix, therefore it is quite soft.
More Information on Wilkingia
- Wilkingia from the Pennsylvanian Atlas of Ancient Life.