Pentagon shaped piece

[cngodles]

When cleaning up rocks I brought home today, I found this little piece that I didn't originally target. It's pentagon shape makes me believe it's for sure a fossil. I've never found anything like it, so I feel like I'm about to get an education here. Perhaps part of a crinoid? Whatever it is, I don't have the experience, yet.

 

Also noticed the indented hole on the top. Maybe part of it, maybe not. It's way too centered I think to not be part of it.

 

 

Underside. It is convex with a small raised ridge along the edge.

 

 

Sideways view of the underside with scale:

 

 

Front view with scale (non focus stacked)

 

 

There is a porous layer on top, which is very similar to crinoids I've seen in the past. I've only ever found stems.

 

 

[Bullsnake]

Perhaps this may help.

 

 

[cngodles]

So pretty sold on this being a calyx piece. Has to be the first one I’ve ever found, that I know of. Do I have any chance of identifying based on shape? Seems to be many polygon shaped pieces on these charts.

[Missourian]

Plus, it appears to be covered with encrusting forams, possibly Tolypammina.

[minnbuckeye]

 

 

@Missourian

Excellent Crinoid key!! I wish one existed for the Mississippian of Iowa as nice as yours. 

 

 Mike

 

[cngodles]

8 hours ago, Missourian said:

Plus, it appears to be covered with encrusting forams, possibly Tolypammina.

Now I'm learning double! Is this the worm like structures on there? I've found several examples of that, and have always wondered if that was a fossil process or a modern day process. You've helped load up my research queue for the week.

[Missourian]

On 1/6/2021 at 7:38 AM, minnbuckeye said:

 

 

@MissourianExcellent Crinoid key!! I wish one existed for the Mississippian of Iowa as nice as yours. 

 

 Mike

 

Steve, I almost forgot about that.

 

Thank you minnbuckeye. Actually, I drew it up myself with a felt-tip pin. It's a miracle I didn't make a mistake. I don't know if I could do that again.

[Missourian]

On 1/6/2021 at 8:37 AM, cngodles said:

Now I'm learning double! Is this the worm like structures on there? I've found several examples of that, and have always wondered if that was a fossil process or a modern day process. You've helped load up my research queue for the week.

 

Here is an example from the Pennsylvanian of Kansas City. These forams are mixed in with algae encrusted on a shell:

 

 

Still, there's a chance yours could be something else entirely.

[minnbuckeye]

@Missourian, Could you enlighten me as to what is algae and what is foram in your picture? My minimal understanding of forams is that of single celled organisms. If such, the tubular structures are the algae? If so, I don't see the forams. And NO, I am not questioning your IDs by any means. Just hate questions in my mind that need answered!!! The only forams in my collection are from Florida and they are small round flat pancakes.

   

Mike

   

 

[DPS Ammonite]

29 minutes ago, minnbuckeye said:

@Missourian, Could you enlighten me as to what is algae and what is foram in your picture? My minimal understanding of forams is that of single celled organisms. If such, the tubular structures are the algae? If so, I don't see the forams.

Wow! It looks like Tolypammina looks sort of like worm tubes.

 

http://yadda.icm.edu.pl/yadda/element/bwmeta1.element.agro-41b16c1b-5e26-48b8-8ac2-fe6cfe13a6d3/c/app18-095.pdf

 

https://www.palass.org/sites/default/files/media/publications/palaeontology/volume_11/vol11_part4_pp601-609.pdf

 

Edited January 8, 2021 by DPS Ammonite

[cngodles]

Sort the same deal here on this Metacoceras and Solenochilus?

 

[minnbuckeye]

 Doing a bit of looking, I now understand some forms of forams construct calcium carbonate tubes in which algae live with them in a symbiotic relationship. This would make sense to me when I look at the specimen now. Did I interpret articles correctly?? 

 

The Foraminifera ("forams") are among the largest and most abundant of all unicellular organisms. They can reach 20 cm in length and 18 cm in width, and the shells surrounding them are even bigger, up to 30 cm in length.      Ebio 

 

 Reef-dwelling large benthic foraminifera (LBF) are single-celled protists that build a calcium carbonate (CaCO₃) test and harbour algae as photo-symbionts.   Microbiome

[Missourian]

6 hours ago, minnbuckeye said:

@Missourian, Could you enlighten me as to what is algae and what is foram in your picture? My minimal understanding of forams is that of single celled organisms. If such, the tubular structures are the algae? If so, I don't see the forams. And NO, I am not questioning your IDs by any means. Just hate questions in my mind that need answered!!! The only forams in my collection are from Florida and they are small round flat pancakes.

   

Mike

 

Sorry for the sparse details.

 

The algae is the 'matrix' containing the tubular forams. It is sometimes called Ottonosia. Some examples:

 

[Missourian]

2 hours ago, minnbuckeye said:

 Doing a bit of looking, I now understand some forms of forams construct calcium carbonate tubes in which algae live with them in a symbiotic relationship. This would make sense to me when I look at the specimen now. Did I interpret articles correctly?? 

 

The Foraminifera ("forams") are among the largest and most abundant of all unicellular organisms. They can reach 20 cm in length and 18 cm in width, and the shells surrounding them are even bigger, up to 30 cm in length.      Ebio 

 

 Reef-dwelling large benthic foraminifera (LBF) are single-celled protists that build a calcium carbonate (CaCO₃) test and harbour algae as photo-symbionts.   Microbiome

 

Yeah. Now that I remember, there are two types of these forams -- calcified and agglutinated.

 

Agglutinated -- Fragments (silt grains, shell fragments, other tests, etc.) to construct the test. Tolypammina belongs in this group.

 

Calcified -- The test is deposited calcium carbonate. Calcitornella is the calcified equivalent of Tolypammina.

 

I've leaned toward my forams as the agglutinated variety, based on identifications of specimens in publications and the coloration and the chalky white near-opacity of the specimens.

[Missourian]

8 hours ago, cngodles said:

Sort the same deal here on this Metacoceras and Solenochilus?

 

Yes. Very nice examples!

[cngodles]

I like to come back to these threads and post better photos. The contrast reveals the textured pattern on the convex, outer side. Scale bar = 5 mm.