A friend's mystery from Maine

[MeargleSchmeargl]

I return once again to the Forum.

 

Recently I was asked about something which someone on Discord found in Maine. Honestly, I'm not quite sure what to think of it as I'm not entirely familiar with the geology surrounding Maine:

 

 

What my Discord companion does know is the area which they found it in, right around Caribou by the local river, which appears to be underlain by Silurian strata (based on Rockd)

 

 

I'd love to get to the bottom of this mystery!

 

[Tidgy's Dad]

I think it's an external mold of the tabulate coral Heliolites. 

[Rockwood]

It could also be from the Chapman formation. Exposures are along a river. That may be closer to Presque Isle though. It's been a while since I've been up there, and I can't get at any reference to it right now. 

[EMP]

On 3/19/2023 at 4:07 PM, MeargleSchmeargl said:

I return once again to the Forum.

 

Recently I was asked about something which someone on Discord found in Maine. Honestly, I'm not quite sure what to think of it as I'm not entirely familiar with the geology surrounding Maine:

 

 

What my Discord companion does know is the area which they found it in, right around Caribou by the local river, which appears to be underlain by Silurian strata (based on Rockd)

 

 

I'd love to get to the bottom of this mystery!

 

 

On 3/19/2023 at 4:09 PM, Tidgy's Dad said:

I think it's an external mold of the tabulate coral Heliolites. 

 

I've found similar stuff in the Red Mountain Formation in North Georgia. I always thought they were bryozoans of some sort, but it's interesting that they could be corals instead considering the depositional environment. 

[Rockwood]

1 hour ago, EMP said:

 

 

I've found similar stuff in the Red Mountain Formation in North Georgia. I always thought they were bryozoans of some sort, but it's interesting that they could be corals instead considering the depositional environment. 

These shapes are too large to be bryozoans, and I don't think it's been established that they even came directly from a known formation. It's very likely that it was found in glacial material.