Limestone Fossil from Eastern Anatolia

[defender]

The following set of photographs is of a roughly 5-inch x 5-inch x 7-inch limestone fossil.  I found it in Eastern Anatolia along the Turkish-Iranian border near the village of Uzengili.  It exhibits striations from what I call "top" to "bottom", although there are some (only 2 or 3) horizontal striations that seem to have a replacement material akin to quartz, in that it appears clear (but very thin).  At first I thought this was a coral, but I am beginning to wonder if it is a Stromatoporoid Sponge... however, it could be something entirely different, and that I why I am presenting photos of it in this forum to see if anyone recognizes this morphology.

 

The following photographs show the fossil in rotations of 90 degrees (which I have labelled North, East, South, and West for reference).  I also have a "top" and a "bottom" view, although what I label as the "top" may actually be the "bottom" if it turns out to be a sponge and not a coral.

 

Of note are some tiny features along the "bottom".  These features may be part of the fossil, ore perhaps they are growths of some other material that has leached out of the soil and onto the fossil.  These features seems quite well integrated with the rest of the limestone.  What is curious is the fact that the "bottom" looks like it is a fracture, in that it is smooth with few features other than some parallel striations.  To have these intricate features survive on a fracture plane seems odd to me and that I why I am suggesting that they may be leached material.

 

I am an engineer and not a geologist or paleontologist, so some expert identification help would be appreciated.

[defender]

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[Ludwigia]

It appears to me at first look to be a broken and weathered sedimentary stone of some sort. What you call "quartz" may very well be calcite. You could try the acid test there with citric acid to see if it bubbles. I'm not sure if those features are fossiliferous or mineralogic in origin. Let's wait and see what others have to say. By the way, did you know that if you get caught taking anything that even looks like a stone, let alone an artifact, even a natural one, out of Turkey, you would more than likely be slapped with an exhorbitant fine or even end up in jail? Or are you in the forces?

[westcoast]

Looks like poorly preserved colonial coral.

[FossilDAWG]

I agree with heavily recrystallized colonial coral.

 

Don

[defender]

8 hours ago, Ludwigia said:

It appears to me at first look to be a broken and weathered sedimentary stone of some sort. What you call "quartz" may very well be calcite. You could try the acid test there with citric acid to see if it bubbles. I'm not sure if those features are fossiliferous or mineralogic in origin. Let's wait and see what others have to say. By the way, did you know that if you get caught taking anything that even looks like a stone, let alone an artifact, even a natural one, out of Turkey, you would more than likely be slapped with an exhorbitant fine or even end up in jail? Or are you in the forces?

Ludwigia, I did try hydrochloric acid and it bubbles, but I can't tell if its the surrounding limestone or the calcite (I'm pretty sure its NOT quartz, I just used that to describe the appearance.  I don't think its sedimentary because the striations radiate out in all directions from the "top" and get wider as they spread out toward the "bottom"... not what I would expect from layered sedimentary stone.  Regarding removal of items, I was with the Turkish geologist over the area at the time (faculty at a local university there) and I am faculty at a major U.S. university, so transfer of materials was sanctioned.  His opinion was that this was weathered coral, but as I inspected it, being somewhat familiar with modern coral formations as a diver and a keeper of a marine aquarium, I began to question if this were not instead a sponge rather than a coral.  Hence, my presentation here to get 2nd, 3rd, and 4th opinions.

[defender]

9 minutes ago, FossilDAWG said:

I agree with heavily recrystallized colonial coral.

 

Don

Don and "westcoast", if it is indeed a recrystallized colonial coral, do you think that the items circled in the "Features" picture are part of the colony, or something that has grown on the surface during or after the fossilization process?

[Ludwigia]

The whole stone appears to me to be sedimentary, but it's so strongly crystallized that it's difficult to make anything out except for those features, which are reminiscent of coral. I however don't see anything there which would make me think sponge. Glad to hear that you took it out on a legal basis.

[FossilDAWG]

The circled "features" are (to me) suggestive of septa in corallites that are less recrystallized than the majority of the specimen.  However even they have had their structure altered to some degree, if indeed they are corallites and not mineral growths or even organic features such as lichens.  The best way to be certain if this is a coral would be to have thin sections cut, or at least to make an acetate peel.  That would involve making a cross section, grinding/polishing it absolutely flat, then lightly (briefly) etching it with dilute acetic acid to bring out any structure reflected in differential acid solubility.  After thorough rinsing and drying, you can apply a solvent such as acetone and firmly press a sheet of acetate on the surface.  The acetone softens the acetate, so it picks up an impression of the surface.  The acetate can then be examined under a microscope to see if corallites are visible.  Note that this will work only if the specimen is calcarious and not silicified.  The acetate peel method is somewhat quicker/cheaper, but less detailed than actual cross sections.  If it turns out to really be coral, and should you need to ID the genus/species, you will probably need to get thin sections of longitudinal and cross sections made.

 

Don

[Fossildude19]

I'm in the coral camp here as well. 

 

 

 

 

[westcoast]

fossildawg has summed it up nicely

[abyssunder]

That is a very interesting specimen.

Considering that we don't know the geological time or stratigraphic section of the location of your find,  I think, that the 'key' would start from the upper part presented in the first picture (showing radial and transversal (growth) lines), which could be the lower part of the evolving ensemble. I would exclude sponge, but the remaining possibilities might be rudist lower valve or bouquet of them (encrusted by coral or something else), other bivalve (like Spondylus in a weathered condition), or coral. You have to make at least one thin transverse section to the whole specimen, at (to say) 1cm distance from the larger end, to exclude one of the possibilities.