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Pippa

Oh blast! Am I seeing things that aren't there?

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Pippa

Anyone else see a badly worn and deeply buried blastoid here? Four out of five points are visible. And where the fifth should be, the rock is broken off.

Just my overactive imagination?

Please tell me what you think. Is there possibly a blastoid in this rock?

 

Reasons against this being a blastoid: 

Guidebooks about Great Lakes fossils do not mention blastoids. Googling "blastoid and Lake Michigan" brings up nothing.

It's maybe too large to be a blastoid? The diameter is 4cm. 

 

On the other hand:

Just because fossil books and Google don't mention them doesn't mean that much. I've found rocks at Lake Michigan beaches that I've never seen mentioned in association with Lake Michigan. So, who knows...?

Both geological surveys from Illinois and Wisconsin mention them. So they definitely grew in the shallow ancient sea that used to exist here.

 

Anyway, if there isn't a blastoid within that rock, what is?  

 

seen from "top"

5df5e142b5203_P1000690A.thumb.JPG.2193cbda61a36126ba41656b6387e6f8.JPG

 

5df5e22821709_P1000700B.thumb.JPG.755549c215df0ab933dfd422a8422adf.JPG

 

 

seen sideways:

5df5e2b7c2524_P1000694C.thumb.JPG.1ed9e891ad6b0ba030b9c0eee62987b2.JPG

 

 

bottom:

5df6463c1f607_bottomP1000705.thumb.JPG.300dbd9cd16f9d99c373b5ea860f3586.JPG

 

 

 

 

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Ludwigia

I'm not seeing a blastoid there, just imbedded crinoid bits, but the photos aren't the best quality, so I can't make out any proper details anyway.

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minnbuckeye

No blastoid, though looking at the whole specimen, I understand your thought process. Blastoids typically are not that large. And the presence of crinoid bits within the "blastoid" looking rock lessen the chances even further. Finally, blastoids are not found in the area. So I would relabel this as a water worn piece of crinoidal hash. Still a nice find.

 

 Mike

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Archie

+1 for worn piece of crinoidal limestone

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Pippa

Well, I have more hash than I ever need and believe me, this is not a "nice find" as hash goes.

 

Thing is, natural rocks don't typically form pentoid shapes with prominent ridges and depressions between those ridges.

Something IS in that rock and I don't know of any other fossil with a pentoid shape.

As I said above, just because blastoids are not associated with Lake Michigan, means very little to me at this point. With a few exceptions, such as searching for Petoskey stones (hexagonaria), serious fossil hunters do not go to Lake Mich. beaches to find fossils. Actually, I believe even the best Petoskeys are found in rivers after the spring thaw. You see, with the glaciers and more recently the lake having done their thing, very few fossils are found in good enough shape to be keepers, or can even be recognized as fossils.  

 

I do apologize for the bad quality of the photos. I have no special lights, just using the ceiling LEDs that make everything look overly shiny, and dull when I try to soften the light. Plus it's too cold and the weather has been too nasty to take the rock outside. Brr...  

 

Here, I've marked the ridges in red. The area that I think was broken off is marked by the white broken line. 

Maybe that helps y'all to see what I see.

5df66cda9254e_P1000690A.thumb.JPG.ac7f9e0cafb755afeaa710cbc1277681.JPG

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connorp

I agree with the above posters, just crinoidal hash. Looking at all the picture of the bottom especially, the symmetry does not appear to be consistent throughout the rock. No blastoid here.

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Ludwigia

Yes, I can see what you mean, but I'm afraid that it's just wishful thinking, or as you concede yourself in your opening post, the result of an overactive imagination :) Who says that rocks cannot be eroded into such shapes? I've seen enough of them myself in my career.

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Pippa

Well, thanks everyone for telling me what you think. You all are probably correct... sigh.   

 

Yet, despite everything you all said above..... I still have lingering doubts.

I just need to know what this thing looks like inside. So, as the rock isn't a keeper for the couple of crinoid bits, I'm planning to cut it open with my tile saw this winter,  see what it looks like inside.

I haven't ever done anything like that, so it'll be a bit until I've unearthed the tile saw in the basement and will have it rigged to hold rocks securely during cutting... wish me luck!

 

I'll be posting photos if anything interesting should appear.  :-) 

 

Cheerio!

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Pemphix
On ‎15‎.‎12‎.‎2019 at 5:46 PM, Archie said:

+1 for worn piece of crinoidal limestone

+1 more...

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minnbuckeye
4 hours ago, Pippa said:

I'm planning to cut it open with my tile saw this winter

 

My suggestion is a hammer over a saw. By chance if there is a nice crinoid or other keeper inside, it is possible it may break along the fossil. But with a saw, it is going to cut through anything inside. Use "light" taps all around the specimen until it fractures.

 

Mike 

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Pippa
3 hours ago, minnbuckeye said:

 

My suggestion is a hammer over a saw. By chance if there is a nice crinoid or other keeper inside, it is possible it may break along the fossil. But with a saw, it is going to cut through anything inside. Use "light" taps all around the specimen until it fractures.

 

Mike 

Will do.  Thanks for the tip!

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minnbuckeye

Now that I think about it, if it were me, I would even prefer to put it in a vice and apply pressure till it cracks. the pressure tends to split along the fossils inside even better than a hammer.

 

 Mike

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hndmarshall

i would file away at the highest point of your diagram it could be the anchor/base of the plant covered in the hash??...just a guess mind you I am no expert but that is what i would look at as I have come across several such shapes on my search.

 

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T. nepaeolicus
10 hours ago, Pemphix said:

+1 more...

+1 more

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Pippa
9 hours ago, minnbuckeye said:

Now that I think about it, if it were me, I would even prefer to put it in a vice and apply pressure till it cracks. the pressure tends to split along the fossils inside even better than a hammer.

 

 Mike

Aha!

We do have a vise. Come to think of it, I have plenty of hash rocks that might be candidates for a vise treatment.... 

Much easier than digging out the old tile saw and set it up, water and all. I prefer it to the hammer method too, as one has so little control there. 

Good thinking, Mike! 

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Pippa
3 hours ago, hndmarshall said:

i would file away at the highest point of your diagram it could be the anchor/base of the plant covered in the hash??...just a guess mind you I am no expert but that is what i would look at as I have come across several such shapes on my search.

 

Yes, great idea. Thank you for the tip.

Have you successfully uncovered fossils by filing away at possible protrusions? What have you found?

I'll set the stone into the vise as Mike suggested above, but I'll give it a bit of a shave first, see what unfolds before applying additional pressure. 

 

 

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