<p>The image below was taken on a hike.  Circular patterns at bottom (it is flatter on this face and round otherwise) appear either man-made or possibly it is a fossil.  </p>

<p>Any idea what this could be?</p>

<p><a href="https://i.sstatic.net/09t1N.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/09t1N.jpg" alt="Rock of interest:"></a></p>

CC BY-SA 3.0
2017-01-17T18:42:35.090Z
Welcome to Earth Science StackExchange! Could you provide a bit more information? Please follow this guide: http://meta.earthscience.stackexchange.com/a/125/56.
arkaia
CC BY-SA 3.0
2017-01-17T22:59:30.833Z
I don't suppose you have a picture of the chipped side. It's useful to see an unweathered surface when identifying rocks
haresfur
CC BY-SA 3.0
2017-01-18T08:09:20.313Z
There look to be some radial markings in the centre which lead me to suspect that this is a fossil but I'm no expert on what it could be.
bon
CC BY-SA 3.0
2017-01-18T10:59:25.867Z
OTOH From this single photo with lack of information, this could be concrete
Jan Doggen
CC BY-SA 3.0
2017-01-18T15:29:31.473Z
It could be a concretion having a image of the other side and the broken surface would help a lot. Density and were it was found will help as well. If the other side is broken off you might have a fossil or at least a cast of one.
John
CC BY-SA 3.0
2017-01-18T20:28:40.610Z
The depth of lake or small dirty pool of rain could be create this loop by change of the depth.
Takahiro Waki
CC BY-SA 3.0
2017-01-19T01:00:25.687Z
Thanks for the comments, I apologize of the lack of detail.  It was a long hike a few hours away so by the time I posted and read the guide it was too late for me to take more photos, check hardness, etc...  Probably only other useful information is the rock was at the bottom of a gorge/valley near a creek bed.  Also, scale, that rock is about 14-16" in diameter.
DrTarr
<fossils><paleontology>
Circular patterns at bottom of rock, is it a fossil?
DrTarr
# Circular patterns at bottom of rock, is it a fossil?

(Asked by: username_0 on 2017-01-17)

The image below was taken on a hike. Circular patterns at bottom (it is flatter on this face and round otherwise) appear either man-made or possibly it is a fossil.

Any idea what this could be?

[![Rock of interest:](https://i.sstatic.net/09t1N.jpg)](https://i.sstatic.net/09t1N.jpg)

**Tags:** fossils, paleontology

> **Comments:**
> **username_1**: Welcome to Earth Science StackExchange! Could you provide a bit more information? Please follow this guide: http://meta.earthscience.stackexchange.com/a/125/56.  
> **username_2**: I don't suppose you have a picture of the chipped side. It's useful to see an unweathered surface when identifying rocks  
> **username_3**: There look to be some radial markings in the centre which lead me to suspect that this is a fossil but I'm no expert on what it could be.  
> **username_4**: OTOH From this single photo with lack of information, this could be concrete  
> **username_5**: It could be a concretion having a image of the other side and the broken surface would help a lot. Density and were it was found will help as well. If the other side is broken off you might have a fossil or at least a cast of one.  
> **username_6**: The depth of lake or small dirty pool of rain could be create this loop by change of the depth.  
> **username_0**: Thanks for the comments, I apologize of the lack of detail.  It was a long hike a few hours away so by the time I posted and read the guide it was too late for me to take more photos, check hardness, etc...  Probably only other useful information is the rock was at the bottom of a gorge/valley near a creek bed.  Also, scale, that rock is about 14-16" in diameter.  

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## 0 answers

