Having seen the original pictures and the pictures of the same object once opened up, I am inclined to identify the object as ironstone concretion developed around some isolated, short, vertical "something" (not necessarily a plant root). In particular, the concretion appears to have formed in the early stages of diagenesis, before the compaction of the encasing sediments reached the current stage. The "doming" above the concretion, infact, could be the result of less vertical shortnening of the concretion itself relative to the encasing sediments.

Please let me know if the following reference/site is helpful to you:

http://www.palaeontologyonline.com/articles/2013/patterns-in-palaeontology-exceptional-preservation-of-fossils-in-concretions/

Dennis

Dennis Mazur

Dear Dennis,

Thank you for your respond. The site is truly helpful.

Best regards: Miroslav

Dear Miroslav,

Maybe the shaft of a crustacean burrow, something like Ophiomorpha or, if continental, from a crayfish. Watch out for more, probably horizontal burrows.

Good luck and regards,

Dirk..

Miroslav:

You need to just crack open the concretion to see if it contains any fossil and determine mineral composition, if calcareous or not.

Best

Syed

 Dear Mr. Ivanov,

form the outward expression I interpret this vertical object crosscutting the S planes as biogenic in origin and denominate it as a member of the group of ichnofossils s.l. The reason for that lies within the physical-chemical interaction between host rock, wall rock and object. Concretions have been derived from such interactions and the contact zone can be checked for these migration of intrastratal solutions. As a common evidence haloes or cockade textures come into being.

It is a rather general suggestion to help you identify by yourself in the field which way you should direct your thoughts.

I wish you much success

H.G.Dill

Dear,

I think it is a crustacean burrow (Ophiomorpha). The small concretions around the burrow are peletes.

Miroslav:

Have a look at this link for insights and do make a thin section of the recovered concretion.

Best

Syed

I agree, it looks like a burrow, probably crustacean in origin (Ophiomorpha).

I agree that its position and external morphology point to an ichnofossil. A closer approach should come from breaking/sectioning the specimen.

Best,

Juan

I think it is plankton fossil

Looks like a burrow trace fossil from what I can see from your photographs Miroslav. Is that's its full length or do you know if it continued downwards below the level shown?

Dear all

Thank you for your answers. I crack open the specimen and these are the pictures. Inside the burrow is filled with iron hydroxides ( Limonite). Which is abundant in this sediments.

Best regards: Miroslav

Miroslav:

Your images fail to suggest any features of a Ichnofossil. They instead appear to be simply concretions of abiogenic origin.

Best

Syed

Does not look biogenic; I suspect its an ironstone concretion.

Dear Mr. Ivanov:

You are the person "most closely" to the "limonite" encrustation. I would like to draw your attention to a study which can be downloaded from the RG Server:

DILL, H.G. and MELCHER, F. (2004) Ferrous biogenic structures in swamps of  the Holocene Kathmandu Lake, Nepal – Their implications concerning palaeogeography and physico-chemical disequilibria.- Neues Jahrbuch für Mineralogie Abhandlungen, 180: 193-213.

Try and compare what you saw in your ferricretes  with what we found. Maybe it helps you make some progress with your work and it is a step forward.

I wish you much success

H.G.Dill

Fossil should contain same substance with its surrounding.  

Travertines have a nasty habit of looking like bones. I ran into one in neogene sediments, Euboea, Greece, that resembled a miocene pig's maxilla, with fossa!

With reference to the first three photographs.  The material in question does not appear to be a fossil.  However, it is interesting that in the 3rd photograph it resembles a human face (LOL). From the second lot of 4 photographs it clearly appear to be limonite encrustations as suggested by Prof. H.G. DILL. 

Certainly it involves accumulation of iron, but there appears to be some structure showing in the second set of pictures that resembles that of wood.  A thin section after impregnation with resin should indicate whether the limonite has been deposited on a former structure and also whether it is merely a nodule formed around a fragment of organic origin. These are quite common in present day soils where ferrous iron in soil solutions meets oxygen, e.g., around roots.

Stuart.

This appears to be a concretion, now limonitic, but perhaps originally sideritic in composition.  Note a slight upward bowing of  the overlying sediment which could have occurred during the original growth of  the concretion within the sediment.

It is not so easy to identify weather it is a fossil or a concretion, both cases are possible; however, concretion is more likely 

It is look as concretion.

This does indeed look like a specimen of Ophiomorpha ?nodosa but if it is, then the alluivial interpretation may need revisiting! As Dirk Knaust suggests, some crayfish burrows (freshwater) may superficially resemble marine crustacean burrows. The apparent 'pelleted' lining may in fact be a diagenetic effect as the substrate looks a little too muddy to necessitate a pellet lining to the burrow wall - this is something that happens in loose unconsolidated sands.

Crayfish burrows tend to have a strong horizontal component, I would say that this is a rhizocretion (nodule around a root).

There is a possible Jurassic crayfish trace in here: https://www.researchgate.net/publication/288034120_Palaeoenvironmental_controls_on_the_ichnology_of_tide-influenced_facies_with_an_example_from_a_macrotidal_tide-dominated_deltaic_depositional_system_Lajas_Formation_Neuquen_Province_Argentina

Article Palaeoenvironmental controls on the ichnology of tide-influe...

Duncan:

Unlikely to be a nodule around a root.

Best

Syed

Dear Miroslav,

The figure looks like a trace fossil, the Ophiomorpha suggested by Paul Cummings above,  the node structure of the genus is rather very coarse here. For sure it is a vertical burrow, cutting across the bedding.  I will not call it a concretion.May be a new species of Ophiomorpha.

Obianuju P. Umeji

Miroslav:

Distinct up warping of bedding as pointed out by Richard seems to rule out biogenic nature of such a concretion.

Best

Syed

Miroslav:  

It could be siderite concretion. Such is common in the  Miocene sedimentary rocks in Sarawak.

Having seen the original pictures and the pictures of the same object once opened up, I am inclined to identify the object as ironstone concretion developed around some isolated, short, vertical "something" (not necessarily a plant root). In particular, the concretion appears to have formed in the early stages of diagenesis, before the compaction of the encasing sediments reached the current stage. The "doming" above the concretion, infact, could be the result of less vertical shortnening of the concretion itself relative to the encasing sediments.

I think It is far from concretion or plants root, mostly vertical burrows.

Best wishes

Well, with the seen i think that it is a concretion formed from the residual iron oxides in the area. It is far from a fossil

I do agree with evrybody: it may be many things, But...

A hole made by an animal would be filled with the same clay surrounding it. And it is not.

Could be a root. But if it were, I would expect to see more roots in the same layer level and there is not.

It is too irregular to be a shell of any kind.

The same limonitezation (brown flattened spots) can be seen all around the rock.

It is visible a small transition limonite zone, as Harald observed, surrounding the "thing" and more or less grading from the layer to the "thing".

And as Syed points out, it deformed the upper layer and its surroundings.

All that is possible to say from the photos showed, I am quite confident to say it is not organic. It seems to be a concretion made out of limonite.

I recommend Syed's answer

Best Regards