More than likely the specimens shown in the image are one of the following species: Archimedes distans (Ulrich), Archimedes invaginatus (Ulrich), Archimedes sublaxus (Ulrich), Archimedes meekanoides (McFarlan), or Archimedes mcfarlani (Condra & Elias).
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRYF9x07Hq2DcfOiKKZlNv14Tf8gz2I_SU5tDAVFknQ9T8hw2kT_j1Ou9ItqtteGT9TStcxcE20GXOUdE2uTlohpQ5Rl-xwMh6i2kezdhByg2Hd2MXhGgUQE9MYIc8-j6jxjnV7tC5vWGZ/s400/archimedes+bryzoans.jpg)
More information about Archimedes found at this site can be found at this web page created by a local naturalist at the Falls of the Ohio, Indiana State Park
web page link