Hi there @mark-ryan You can update the Geochron to Eon: Phanerozoic Era: Paleozoic Period: Ordovician. Based on this group’s fossils, this looks like it may indeed be an Ordovician sponge. Here are some resources for further ID research: http://www.fossilspot.com/STATES/MN.HTM…[Read more]

@jbauer any ideas on this one? Seems interesting.

Hi @mark-ryan & @vperez – this is a weird one. I am not sure about stromatoporoid, those are calcified so I would expect better preservation. It’s possible that the circular bit on the ‘bottom’ is a nucleation point for a sponge or something trying to anchor down – so it could be an unrelated animal piece. That star shaped pattern on top is also…[Read more]

Hi @jbauer – Thanks for your comment. Yes, it’s a very weird fossil. I’m mainly stabbing in the dark about these things but it’s been fun doing so. If it is stromatoporoid, the strange star-shaped feature (astrorhizae?), may be part of it or another creature entirely. I don’t think the circular stalk is unrelated to the “mushroom cap” because in…[Read more]

@mark-ryan – this is very interesting. It’s so fun to speculate!!! Especially when everything is so unknown. It’s certainly a possibility that the single star shaped feature is an astrorhizae – but I’ve never only seen one have you? Usually it’s a whole mess across a surface, usually associated with monticules – but these are usuals, there are…[Read more]

@jbauer – Hi Jennifer. I’ve posted several photos of these strange things on my Flickr page which can be viewed here: https://www.flickr.com/photos/rynoceras/albums/72157662532368937
You’ll see a mish-mash of several shots of different specimens which should give you more visual information than my single post here. I get out to Cannon Falls a…[Read more]