Is it natural or carved?

[Danielle 875]

Found at the beach yesterday and I am obsessed with this ai can't stop looking at it it seems to be a carved picture or something on top of some Flint stone what could this be? 

[TqB]

It's part of an echinoid from the Upper Cretaceous (the age of all flint in the UK), a piece of the internal flint mould. Possibly Echinocorys - hard to be sure but the size and pattern fits.

[Danielle 875]

Wow thank you. I love this site you guys are so awesome 

[DPS Ammonite]

14 hours ago, TqB said:

It's part of an echinoid from the Upper Cretaceous (the age of all flint in the UK), a piece of the internal flint mould. Possibly Echinocorys - hard to be sure but the size and pattern fits.

I think that the OP is asking if the unusual pattern of concentric layers and the double row of circles is related to human activity or possibly a fossil. I think that I see rounded layers of agate. Is there an echinoid that has a similar “pattern” of double circles that the agate could have formed around? Do you have a picture?

Edited June 27, 2022 by DPS Ammonite

[Coco]

Hi,

 

At first glance, I thought that the traces of agate and the general shape looked very little like a sea urchin despite the two round alignments. By deepening the more detailed image, we can clearly distinguish the areolas around each button of the row, forming one of the five ambulacres (buttons = parts where the spines cling).

 

So I think it’s an internal sea urchin mold, but so damaged that I can’t say anything more.

 

Coco

Edited June 27, 2022 by Coco

[DPS Ammonite]

I see. So this is a very small portion of an echinoid that shows part of one ambulacra. 

[Coco]

Not especially a small part of sea urchin, rather an internal mold of which only one side is not too eroded to be able to recognize what it is. It is missing perhaps only a few millimeters thick on the rest, but it’s enough to stop seeing the internal structures.

 

Coco

Edited June 27, 2022 by Coco

[DPS Ammonite]

8 minutes ago, Coco said:

Not especially a small part of sea urchin, rather an internal mold of which only one side is not too eroded to be able to recognize what it is. It is missing perhaps only a few millimeters thick on the rest, but it’s enough to stop seeing the internal structures.

 

Coco

I said small because we see only part of one of the 5 ambulacra. At first I thought that we were looking at the greatest part of an internal mold.

[Coco]

Yes, I understood what you meant, but I added my answer so that I could be clearer for the others

 

Coco

[DPS Ammonite]

Clearer is usually better. 
 

Here is a diagram of what part of an echinoid we may be looking at:

 

 

[TqB]

4 hours ago, DPS Ammonite said:

I think that the OP is asking if the unusual pattern of concentric layers and the double row of circles is related to human activity or possibly a fossil. I think that I see rounded layers of agate. Is there an echinoid that has a similar “pattern” of double circles that the agate could have formed around? Do you have a picture?

 

The rings are caused partly by wearing through the internal impression of the areolas to the dark core flint, and see comment below.

 

A similar one from Sussex (hope it's OK to post): 

https://www.facebook.com/groups/345764085874612/permalink/1168362023614810/
In that thread, London NHM echinoderm specialist Tim Ewin states:

 When the acidic flint solution enters the test (before it hardens) it starts to dissolve the calcite skeleton, enlarging the tube feet pores and plate boundaries making for some pretty otherworldly patterns.

 

Edited June 27, 2022 by TqB