Help me id mold fossil please

[Jewell1212]

Please bear with me as I am new to fossil identification.  My 14 year old son recently became interested in fossils and geodes, so I am trying to encourage his interest.  

We found a round rock about the size of a bowling ball recently while digging to install a septic tank and he wanted to break it open to see if any crystals were inside.  When he broke it open, he found some fossils, one of which I believe is called a mold fossil, images attached.  The object that made the imprint appears to have had spines or thorns.  Any help is appreciated!

 

This was found in west central Missouri, SE Henry County.  The imprint measures approximately 4-5 cm long.  The round circle near the imprint appears to be a similar mold fossil, seen end-on.  When he broke open the rock, he apparently split the mold down the middle.  The pictures show both halves.

[Al Dente]

Urchin spine?

[daves64]

Possibly an impression of some coral.

[TqB]

1 hour ago, Al Dente said:

Urchin spine?

My first guess too - some Archaeocidaris spines look just like that. And there's plenty of Carboniferous in Henry County which would fit. Nice find!

[caldigger]

Is there anything on the other parts of the rock pieces?

[Jewell1212]

Thanks everybody! Very cool! We look forward to finding more. 

[Jewell1212]

We are looking into buying a chisel so we can “excavate” the rock further. 

[caldigger]

1 hour ago, Jewell1212 said:

We are looking into buying a chisel so we can “excavate” the rock further. 

What I meant was, when he broke the rock open, were there "things" showing on the other broken pieces?

[Jewell1212]

There were other things showing. I was unaware he had taken another photo and it clearly shows more detail of the urchin. I will post it. We don’t have the rock with us right now. We live in Kansas City and the rock is at our weekend home near Truman Lake. We’ll be bringing it back with us next time we go there. 

[Al Dente]

This last photo shows several spines and plates from an urchin.

[Jewell1212]

2 minutes ago, Al Dente said:

This last photo shows several spines and plates from an urchin.

Yes! Once everybody had identified the imprint as an urchin, I was able to search online for other photos. Then, when my kid showed me this other photo he had taken, I could see the similarities with specimens shown online. Thanks so much!

[TqB]

Nice Archaeocidaris bits. As well as spines and plates, I think you have some of the teeth and/or other elements from the Aristotle's lantern between the plates here, always a good find:

[Tidgy's Dad]

Very nice find.

[Jewell1212]

On 3/31/2019 at 7:09 AM, TqB said:

Nice Archaeocidaris bits. As well as spines and plates, I think you have some of the teeth and/or other elements from the Aristotle's lantern between the plates here, always a good find:

 

Wow! I'm glad you pointed that out. I missed the teeth. Thanks!!

[Coco]

Hi,

 

On 31/03/2019 at 2:09 PM, TqB said:

Nice Archaeocidaris bits. As well as spines and plates, I think you have some of the teeth and/or other elements from the Aristotle's lantern between the plates here, always a good find:

Where can you see teeth or a part of the Aristotle's lantern ? I can't see them

 

Coco

[TqB]

33 minutes ago, Coco said:

Hi,

 

Where can you see teeth or a part of the Aristotle's lantern ? I can't see them

 

Coco

Hi Coco,

I was thinking the wedge-shaped pieces might be parts of pyramids, like nos. 12, 13 &14 here (all the same half pyramid). I admit there are no obvious teeth though.

 

[caldigger]

Coco, I can't belive you don't see those teeth, they are plain as day!

[Jewell1212]

2 hours ago, caldigger said:

Coco, I can't belive you don't see those teeth, they are plain as day!

 

[Coco]

 

I can see now what you mean. But really I don't think it is a part of the Aristotle's lantern.

 

Here you can see that the mouth is in the middle of a soft part, in a "hole" of the "skeleton". I think what you see is an erosion of the sea urchin shell : https://fr.wikipedia.org/wiki/Lanterne_d'Aristote

 

Coco