How many animals is in this rock?

[PaleoOrdo]

I wonder if this is some animal or just a crystal formation. The surface is extremely smooth, when I touch it with my finger. The formation is from Late Ordovician.

Pict. 1

Pict.2

Pict.3

Pict.4

 

 

 

[Kane]

The shape and texture seems similar to a bivalve.

[Tetradium]

30 minutes ago, Kane said:

The shape and texture seems similar to a bivalve.

it fractures like one too. At least two bivalve that I could see. 

[PaleoOrdo]

Yes I agree. Thank you Kane and Tetradium. One of them seems quite big. Not so well preserved and not so much value, but the stone is nice. 

[FossilDAWG]

It's a bit hard to see in the photo, but there seems to be some segmentation in the piece on the right hand side.  It might just be the way the fossil has fractured, but the spacing seem consistent and not random.  Also the color/texture is different from what I normally see in bivalves preserved in this sort of matrix.  I am getting an arthropod vibe from this specimen.

 

Don

[Tetradium]

2 hours ago, FossilDAWG said:

It's a bit hard to see in the photo, but there seems to be some segmentation in the piece on the right hand side.  It might just be the way the fossil has fractured, but the spacing seem consistent and not random.  Also the color/texture is different from what I normally see in bivalves preserved in this sort of matrix.  I am getting an arthropod vibe from this specimen.

 

Don

I know what you means. The seemly regular spaced patterns actually are irregularly spaced and I'm not seeing a trilobite in it. Other types of arthropods may be possible  but you never knows with the colder Baltic Ordovician ocean which tend to be richer in dissolved oxygen.   It look like greywacke a mixture of sand and mud and the fossils are broken up because of the intense pressures put on them.  

[PaleoOrdo]

 

22 hours ago, FossilDAWG said:

It's a bit hard to see in the photo, but there seems to be some segmentation in the piece on the right hand side.  It might just be the way the fossil has fractured, but the spacing seem consistent and not random.  Also the color/texture is different from what I normally see in bivalves preserved in this sort of matrix.  I am getting an arthropod vibe from this specimen.

 

19 hours ago, Tetradium said:

It look like greywacke a mixture of sand and mud and the fossils are broken up because of the intense pressures put on them. 

Thank you Don and Tetradium for your very interesting comments. I will post some more pictures to show which kind of stone it is (pict.3). To me it seems like a limestone but I not know if it is a greywacke rock or not. One picture I post shows some lines at the outer right top edge (pict.2). It seems also one whole structure to me (see pict.1), although some parts seems missing.

19 hours ago, Tetradium said:

Other types of arthropods may be possible  but you never knows with the colder Baltic Ordovician ocean which tend to be richer in dissolved oxygen.

I would like know more about this subject; why is the colder oceans more rich in dissolved oxygen, and what are the implications of this? Does it mean anoxic conditions and that organisms face shrinking habitats and reduction of biodiversity?

Pict.1

Pict.2

Pict. 3 - the thinner side here have a dark brown texture.

The underside thin surface is also brown muddy color but it is dark blue inside the rock and I can see some very small shining crystals in the sunlight when I break away the brown layer. Can it still be greywacke?

 

Edited August 30, 2021 by PaleoOrdo