UPDATE: (8-16-2020): After reading Dave's blog entry about this type of fossil at
http://viewsofthemahantango.blogspot.com/2020/08/mound-like-bryozoan-from-speed-limestone.html it is obvious this bryozoan is not
Eridotyrpa (Ulrich, 1883). I found these after I joined the local geology club and we visited Speed Quarry. They are very numerous and I asked someone what they were called and got that name. Now that I have the
Index Fossils for North America book by Schimer and Shrock 1944. It describes it as a bryozoan having branches. Dave suggests it might be a
Monotrypa sp. (Nicholson, 1879). The
research of H. A. Nicholson (1844-1899) deserves my further attention to see if it can help identify more bryozoan fossils from this area.
Devonian Period bryozoan colonies called
Eridotrypa. These fossils were found in Speed Limestone in Clark County, Indiana. The first fossil shown looks like something was boring into it.
A neat thing to show people is that some of these fossils will float in water. I suppose the small bodied creatures decomposed leaving air pockets. This porous structure is light enough to float until the cavities eventually flood.
