Is this a petrified mushroom cap?

[Diggler2380]

I found this in in. Grove heights , MN. Where a huge amount of land was dug up and now is a construction site. I found it right after the ground was initially turned up . I believe it may of been old farm land or just unused land prior to the dig.

[jpc]

sure looks like one... superficially, but no.  Mushroom cap fossils have only been found in amber and there are thousands of other lookalikes out there that are just piece of concretions.  I am not sure what your is, but certainly not a mushroom cap.  Notice the concentric layers on the inside.  This suggests to me that it is likely a worn concretion.  

[Top Trilo]

Cool rock, that I would of picked up. I agree with above though not from a mushroom.

[Thomas.Dodson]

34 minutes ago, jpc said:

sure looks like one... superficially, but no.  Mushroom cap fossils have only been found in amber and there are thousands of other lookalikes out there that are just piece of concretions.  I am not sure what your is, but certainly not a mushroom cap.  Notice the concentric layers on the inside.  This suggests to me that it is likely a worn concretion.  

Certainly not a mushroom but it might be a dome colony bryozoan. There looks to be Zooecia and those clustered areas (the light color in this case) appears on some bryozoans. The dome ones can also get concentric layers.

[Mainefossils]

Welcome to the Forum, @Diggler2380! I don't think your find is a mushroom - such finds are uncommon and unlikely from your area (here is a website on the subject: https://ucmp.berkeley.edu/fungi/fungifr.html). But I think that a waterworn coral is a possibility because of the pattern on the exterior, and the ringed structure on the inside. I believe that @TqB would be able to help more with this. Would you also mind taking pictures with a ruler for scale, @Coco has made an excellent topic on the subject. Happy Hunting! 

Edited September 29, 2021 by Mainefossils

[Fossildude19]

Cropped and brightened: 

 

 

 

Pictures of the item dry, and from directly above, of all sides - Front, back, right side, left side, top, and bottom will be helpful. 

 

[Denis Arcand]

If it is  bryozoan a close-up view would help the identification

[TqB]

I agree it's a bryozoan. The light areas may be worn monticules.

 

Edited September 29, 2021 by TqB

[Coco]

Hi,

 

6 hours ago, Mainefossils said:

Would you also mind taking pictures with a ruler for scale, @Coco has made an excellent topic on the subject. Happy Hunting! 

Thanks Asher

 

@Diggler2380 I agree with what was said earlier.

As suggested by @Mainefossils read my last link in my signature, and if you don’t have a rule I suggest you print my document and place your future samples on it, taking care to let one of the boxes showing the size appear (teaching message)

 

Coco

[jpc]

I love it when I am wrong.   I know so little about bryozoans, now I know a little more.  

[Ludwigia]

7 hours ago, jpc said:

I love it when I am wrong.   I know so little about bryozoans, now I know a little more.  

The mark of a true scientist!

[Pemphix]

23 hours ago, jpc said:

Mushroom cap fossils have only been found in amber 

Depends, what exactly is defined as "mushroom cap" - there are known (tree-)mushrooms for example from triassic sediments:

1) https://www.researchgate.net/publication/303524598_Nissleria_ilsfeldi_a_fossil_fungus_genus_of_the_German_Lower_Keuper_Upper_Ladinian_Middle_Triassic_from_Ilsfeld_-_Nissleria_ilsfeldi_eine_fossile_Pilzgattung_aus_dem_deutschen_Unter-Keuper_Oberes_Ladi

 

2) Fohrer, E. & Simon, T. (2003): Baumpilze und Trüffel – höhere Pilze aus dem Keuper, Teil 2. – Fossilien 1/03: 19–24; Korb (Goldschneck)

 

3) https://ojs-jh-gfn.ub.uni-stuttgart.de/index.php/jahreshefte/article/view/182

[Tetradium]

14 hours ago, jpc said:

I love it when I am wrong.   I know so little about bryozoans, now I know a little more.  

Here's an addition info. This is Prasopora conoidea. Ordovician bryozoan. Looking up Inver groves heights it borders or are near Mississippi river. Vast majority of highlands in the area is thick glacial till so farm field must be fairly close to the river and at a lower elevation. Most fossil deposits in Twin Cities tend to be within 20 miles of the Mississippi river thou worn limestone with partial fossils and Devonian corals tend to be found in glacial till. Prasopora wont last long before being destroyed by glaciers. 

[Tetradium]

On 9/29/2021 at 10:49 AM, Thomas.Dodson said:

Certainly not a mushroom but it might be a dome colony bryozoan. There looks to be Zooecia and those clustered areas (the light color in this case) appears on some bryozoans. The dome ones can also get concentric layers.

Its Prasopora conoidea. Very common in upper Decorah shale layers and since Decorah shale tend to decays into clay fairly fast it wont take long for farmers to dig up fossils.