Another Mystery Slab

[Northern Sharks]

I was on another hunting trip yesterday, again mostly for minerals, but shortly before leaving found a pile full of corals. Slabs like this were quite abundant, as well as what I would call normal looking coral. In the first pic, the round objects are that normal coral, but it's the other shapes I'm not too sure about. They vary in size but none are much bigger than 1". Some that are exposed have a structure similar to coral inside, while the others look like, for lack of a better term, fossil hay. The group leader simply called them worm casings, but I don't think that's correct and when I showed him the structure, he agreed. The area was near Niagara Falls and right around the boundary between Ordovician and Silurian. There were also all kinds of crinoid stems to be found as well as minerals such as Galena, Calcite crystals, Dolomite, Sphalerite, Fluorite, Selenite and others. Thanks as always for the help

[Guest solius symbiosus]

by the second pic, trepostomate bryzoa

[Archimedes]

the second picture is very nice and are Bryozoa

You can probably find Shrimer and Shrock, Index Fossils of North America at your local library and look at all the varied forms of Bryozoa

[geofossil]

I agree with the above identifications with a slight reservation. In Silurian and especially Devonian formations there are some bryozoan and tabulate corals that evolved an outward similarity. Some of the Coenites, etc. are classified among tabulate corals but this is not universally accepted. I've collected some specimens and identification wasn't possible as coral or bryozoan until I did a cross section and then had the 'Devonian coral guy' examine them. Even after close examination, however, some tabulate corals are 'lumped in' with Coelenterata as much for conveniece as anything...they don't have much diagnostic structure and may be more related to bryozoans.

If you get out to Alberta from Ontario, then be sure to visit some of the high valleys in the Rockies. In some Devonian formations (two scenery photos) almost every rock has bryozoans and tabulates (like the third photo) and other fossils:

[Northern Sharks]

Thanks for the help guys. If anyone is interested, I have a smaller piece of the same material that I'd be willing to trade. Send me a PM if you want more details.