Wood, Bone, Clay, what is this ?

[Brevicollis]

Hello, I found this piece a couple of years ago on a school trip to a nearby creek.

I dont know, what it is, but its definitly mineralised. It also has some interesting round patterns on one side, the cross section appaers to be layered.

It reminded me of tree bark, or bone, but I dont know of any finding locations of these here, and fossil wood from around the area looks completly different. I found two more of these rocks, with the exact same colour, structure, e.t.c. but I dont know where I put them. Has anyone an Idea, what this is, if its organic or geologic origin ?
Thanks if somebody knows !

Edited May 8 by Brevicollis

[val horn]

I do not believe it to be bone wood or clay  i am thinking looking at one side that it may be a colonial rugosa coral.  Where was it found what age are the rocks  rugosa coral will be too old for some locations and too young for others

[Brevicollis]

@val horn

 

Well, I found this in a man made draining creek, where normally no rocks are or should be. Looking at the geological history, and the fact that I found two more of this kind of rock in the glacial deposits, wich are here in nothern Germany just a couple of centimeters below the surface, I think its was brought here during the ice ages by the glaciers. So it must have its origin somewhere in the nordics.

Edited May 9 by Brevicollis

[val horn]

glacial erratics are by definition from somewhere else.  I judge by the the tiny columns, the circular arrangements and the multiple circular units, that it is a colonial rugosa coral.  I dont know anything about European geology to know if that is possible.  There are European members who should know more .

[Carl]

It has the look of partially burned coal to my eye.

[Brevicollis]

I had also thought that it might be peat ?

Was a very popular heating source around 100-??? years ago here.

[val horn]

i would expect peat o fall apart in water, and to burn if dry.