Devonian (?) mystery fossil - Lake Michigan

[J Belian]

Hello. I spend a month every year in Leelanau County, Michigan, USA (the tip of the pinky of the mitten), where fossils are lying all over the place. Some I can ID, some I can’t, no big deal, but this one is making me nuts. It is such a distinctive shape, and these appear frequently n basalt rocks that have tumbled to shore. A local rock shop owner said it was a horn coral - and perhaps it is, but I’m not yet persuaded (but always open to facts). 
 

I am not even remotely a scientist- I’m a law professor - but I have tried to follow instructions as best I could. If anyone needs a different view or a retake, please just say so and I will oblige. The rock is very much not flat, so focus is tricky. 
 

The rock was found in the western shore of Leelanau County. It is dark gray (black when wet - probably basalt) and the fossil or fossil imprint is nearly white. I’ve seen dozens of these white things measuring about 2-3cm long, but this one is roughly 6cm by 3cm wide and appears to be about 1cm thick, though that’s harder to tell. I can see striations in the impression that remind me of perhaps a coral, perhaps a jellyfish-sort of thing. 
 

I’ve taken the best photos I could, in different lighting, but if these are too shabby, I can ask a photographer friend to haul out the big guns. I’ve also taken a couple with the stone wet, to show what they look like on the shoreline. In addition, I took photos of some other fossils embedded in the same rock in case those contextual clues help. Each of those is about 1.5cm long. It almost looks as if someone tried to chip the fossil out, but that seems unlikely, given its location.

 

I know that all the shoreline of Leelanau County is Devonian, but of course, rocks that roll in off Lake Michigan could be from Wisconsin, and that coastline is mostly Silurian (or possibly Ordovician and Cambrian). For that matter, rocks could conceivably come from almost anywhere on Lake Michigan, but given how prevalent these are, I suspect they are from wherever one would expect them to be from. (Lots of help, eh?)

 

I’ve never found any fossil in this area that didn’t look like either a Brachiopod, or Crinoids, or something squishy. Not only does no one I’ve asked have any opinion about this, they aren’t even curious. Don’t know why it’s bugging me - maybe because although I've seen 50+ of these, I can’t find any photo in any book or in any site (so far) that looks anything like it. 
 

My best guess is a fossilized Pac Man ghost. I’m hoping one of you has a better idea.  (I hope .jpeg is as good as .jpg but let me know if not).
 

cheers and thanks!

 

- Julia

 

 

[Rockwood]

These things bugged me for a long time. They rarely display clear evidence of septa. I eventually came to the conclusion that they must be horn corals. 

That would have to be sandstone instead of basalt though. 

[Kane]

Yes, horn coral, thoroughly abraded.

[J Belian]

I appreciate the replies. I’ve seen lots of horn corals - fully excised from the matrix - and they always look - well, like a horn: A single cone. Cannyall help me understand how to see a horn coral here? Because I see nothing hornlike about this. Please understand, I am not disagree with you - I have no basis to do so! - but I just can’t see how this could be the same thing as those. I’m attaching a photo from Wikicommons to illustrate my problem. 
 

I really want to “see” this. Thanks!

[Kane]

They can appear crushed, broken, toppled, and sheared at any angle from erosive forces.

[Rockwood]

What I read is that some horns appear to be adapted to rough conditions. Stout with a robust theca. 

[J Belian]

Thank you all. So are these fossils - which appear to have two apical ends, actually cross-sections of the coral? That’s the only way I can make sense of them.

 

Also - can such fossils ever be extracted from the matrix? Or is that really not worth the bother?

[ynot]

3 hours ago, J Belian said:

Also - can such fossils ever be extracted from the matrix? Or is that really not worth the bother?

They can be but usually are not as they are very common fossils.

[Rockwood]

4 hours ago, J Belian said:

So are these fossils - which appear to have two apical ends, actually cross-sections of the coral?

I think this is a somewhat oblique longitudinal section. The apical end may have been rounded, but there would be only one. The examples I collected in Devonian rocks in Maine looked like a V shape nested in a U-shaped cup.