RockCaCO3 Posted August 18, 2016 Share Posted August 18, 2016 Here's one I'm having a hard time with, its an ID requested by a friend and unfortunately I only saw it long enough to snap 2 pictures on a phone with no scale bar (I know, for shame). It is ~3-4" long. The provenance is fuzzy, but was reportedly pick up in "Southeast" Texas. My 1st thought, given the location was some type Cretaceous scleratinia coral. Although, the 'corallites' aren't regularly spaced. The bluish-white mineral replaced(?) portions almost look like some images I searched on Syringopora (Paleozoic coral). Another thought was crinoids in matrix, but they don't look exactly like crinoids and on the right of the image note the rounded cavity where they are absent. So maybe they are some type of reworked, replaced fossil in a background matrix. After looking at the pictures, I'm also wondering if both portions (circles and background) are not fossils and some type of mineral formation. Anyone seen anything like this before? Any ideas are appreciated. Thanks RockCaCO3 Link to comment Share on other sites More sharing options...
CraigHyatt Posted August 18, 2016 Share Posted August 18, 2016 (edited) Anyone seen anything like this before? Any ideas are appreciated. Thanks RockCaCO3 Why yes. Yes we have. :-) Probably crinoids. See this for comparison: http://www.thefossilforum.com/index.php?/topic/67575-crinoid-or-vertebrae/?hl=crinoid Edited August 18, 2016 by CraigHyatt Info: Craig Hyatt, retired software/electrical engineer Experience: Beginner, fossil hunting less than a year Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert Formation: Escondido, Marine, Upper Cretaceous Materials: Sandstone, Mudstone, Shale, Chert, Chalk Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus Reference: http://txfossils.com/Txfossils.html Link to comment Share on other sites More sharing options...
tmaier Posted August 18, 2016 Share Posted August 18, 2016 Not crinoids... At arm's length, and a passing glance, it looks like a cross section of a coral colony. But! Zoom in and the objects are roughly spherical, and they form clusters of two or more, and they have a halo of some very fine material surrounding them. It would be nice to have a high resolution photo, there is fine detail that is important here. And given their small size, I'm going to take a wild guess that these are some type of protists, like very large forams. And their "shells" are too thick, so maybe the have geodized to become thicker. and the halo is some spicules surrounding the test. Very interesting. Link to comment Share on other sites More sharing options...
Al Dente Posted August 18, 2016 Share Posted August 18, 2016 My guess is these are minerals and not fossils. Looks like radial crystals in matrix. 2 Link to comment Share on other sites More sharing options...
CraigHyatt Posted August 18, 2016 Share Posted August 18, 2016 (edited) Foraminifera seems doubtful to me based on the size. On the other thread the wiki article said most were < 1 mm. Putting the sample size at 3.5 in (90 mm) and counting roughly 13 discs across makes the disc (or sphere) size about 7 mm. I hear what you are saying about the size expansion and spicules though. What excludes the Crinoid diagnosis? Couldn't the apparent spherical impressions have been disc shaped and then rounded by erosion? Edited August 18, 2016 by CraigHyatt Info: Craig Hyatt, retired software/electrical engineer Experience: Beginner, fossil hunting less than a year Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert Formation: Escondido, Marine, Upper Cretaceous Materials: Sandstone, Mudstone, Shale, Chert, Chalk Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus Reference: http://txfossils.com/Txfossils.html Link to comment Share on other sites More sharing options...
tmaier Posted August 18, 2016 Share Posted August 18, 2016 Foraminifera seems doubtful to me based on the size. On the other thread the wiki article said most were < 1 mm. Putting the sample size at 3.5 in (90 mm) and counting roughly 13 discs across makes the disc (or sphere) size about 7 mm. I hear what you are saying about the size expansion and spicules though. What excludes the Crinoid diagnosis? Couldn't the apparent spherical impressions have been disc shaped and then rounded by erosion? Forams the size of a dime... The photo is fuzzy, but crinoids wouldn't have that halo of material around them, and they would not be joined together. That joining looks like "cocci" formations commonly found when simple life forms join together to make colonies. I'm sticking with some type of planktonic cocci critter. http://www.google.com/search?q=plankton+cocci&btnG=Search&hl=en&gbv=1&tbm=isch 1 Link to comment Share on other sites More sharing options...
CraigHyatt Posted August 18, 2016 Share Posted August 18, 2016 Forams the size of a dime... Lepidocyclina.jpg The photo is fuzzy, but crinoids wouldn't have that halo of material around them, and they would not be joined together. That joining looks like "cocci" formations commonly found when simple life forms join together to make colonies. I'm sticking with some type of planktonic cocci critter. http://www.google.com/search?q=plankton+cocci&btnG=Search&hl=en&gbv=1&tbm=isch Thanks. Info: Craig Hyatt, retired software/electrical engineer Experience: Beginner, fossil hunting less than a year Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert Formation: Escondido, Marine, Upper Cretaceous Materials: Sandstone, Mudstone, Shale, Chert, Chalk Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus Reference: http://txfossils.com/Txfossils.html Link to comment Share on other sites More sharing options...
JohnJ Posted August 18, 2016 Share Posted August 18, 2016 My guess is these are minerals and not fossils. Looks like radial crystals in matrix. I agree. This looks like calcitic 'soda straws' that have been encapsulated by the growth of another calcite formation...all in cross-section. 1 The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
tmaier Posted August 18, 2016 Share Posted August 18, 2016 I'm not seeing it... http://www.google.com/search?q=calcitic+%27soda+straws%27+&btnG=Search&hl=en&gbv=1&tbm=isch Do you have some examples? Link to comment Share on other sites More sharing options...
CraigHyatt Posted August 18, 2016 Share Posted August 18, 2016 I agree. This looks like calcitic 'soda straws' that have been encapsulated by the growth of another calcite formation...all in cross-section. How to explain the matrix surface craters? Don't those imply small spheres or discs? Info: Craig Hyatt, retired software/electrical engineer Experience: Beginner, fossil hunting less than a year Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert Formation: Escondido, Marine, Upper Cretaceous Materials: Sandstone, Mudstone, Shale, Chert, Chalk Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus Reference: http://txfossils.com/Txfossils.html Link to comment Share on other sites More sharing options...
JohnJ Posted August 18, 2016 Share Posted August 18, 2016 How to explain the matrix surface craters? Don't those imply small spheres or discs? Ahh...missed the "craters" on a quick glance to start. That certainly rules out the soda straws. Good catch. Still, these look like calcitic formations in various angles of cross-section. The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
tmaier Posted August 19, 2016 Share Posted August 19, 2016 They seem to be spherical... or is that an optical illusion? Is there a side view? I would be tempted to take the dremmel and cut a cross section from it. Link to comment Share on other sites More sharing options...
CraigHyatt Posted August 19, 2016 Share Posted August 19, 2016 I can't make a definitive call, but I am leaning 60/40 in favor of spherical based on subtle details in the images. I am still intrigued by the radial lines that tmaier pointed out. You'd think it was a moonscape. These are the parts that lead me toward spherical. Info: Craig Hyatt, retired software/electrical engineer Experience: Beginner, fossil hunting less than a year Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert Formation: Escondido, Marine, Upper Cretaceous Materials: Sandstone, Mudstone, Shale, Chert, Chalk Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus Reference: http://txfossils.com/Txfossils.html Link to comment Share on other sites More sharing options...
ynot Posted August 19, 2016 Share Posted August 19, 2016 Just another thought-- The circular parts are some type of fossil and the radiating part that surrounds the round part is calcite crystallization. A mix of both worlds. Tony Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
abyssunder Posted August 19, 2016 Share Posted August 19, 2016 (edited) I agree with Tony.Unfortunately, we don't know exactly the location of the find, or the geological age of the area. Without any of this data everything is just a guess.Maybe the recrystallized matrix is older than Cretaceous, could be Paleozoic?So, there could be fused spherical fossils in the matrix, like sponges, for example Girtyocoelia in cross section. (?) Edited August 19, 2016 by abyssunder " We are not separate and independent entities, but like links in a chain, and we could not by any means be what we are without those who went before us and showed us the way. " Thomas Mann My Library Link to comment Share on other sites More sharing options...
RockCaCO3 Posted August 19, 2016 Author Share Posted August 19, 2016 Thanks for the feedback! I'll see if I can nail down the locality and of course get some better pictures with an actual camera with scale and determine the mineral type of the matrix (appears to be calcite?) and the circles (chert?). I'm also going to see if they'll let me try and remove one of the apparent sphericules. I'm currently leaning towards mineral origin for both elements. Thanks again. Link to comment Share on other sites More sharing options...
Fletcher Posted August 19, 2016 Share Posted August 19, 2016 The way they're fused and the craters remind me of agate eyes - this doesn't look like an agate but I imagine hemisphere 'eyes' can form under other circumstances. If the matrix is calcite, I know that's something that forms in vesicules, which supports the eye idea...but I don't know enough about these processes to suggest anything more specific. Link to comment Share on other sites More sharing options...
CraigHyatt Posted August 19, 2016 Share Posted August 19, 2016 (edited) I'm going against the grain and thinking something biogenic like radiolarian. It looks to me that no matter what the matrix wear angle is, the projection to the matrix surface and the internal cross section of the bodies is the same. That suggests a spherical and spiked form to me. That's my story and I'm stickin' to it. :-) Edited August 19, 2016 by CraigHyatt Info: Craig Hyatt, retired software/electrical engineer Experience: Beginner, fossil hunting less than a year Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert Formation: Escondido, Marine, Upper Cretaceous Materials: Sandstone, Mudstone, Shale, Chert, Chalk Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus Reference: http://txfossils.com/Txfossils.html Link to comment Share on other sites More sharing options...
TqB Posted August 19, 2016 Share Posted August 19, 2016 (edited) I'm leaning towards mineral at the moment, with spherulitic crystal groups. Edited August 19, 2016 by TqB 1 Tarquin Link to comment Share on other sites More sharing options...
fifbrindacier Posted August 20, 2016 Share Posted August 20, 2016 Foraminifera seems doubtful to me based on the size. On the other thread the wiki article said most were < 1 mm. Putting the sample size at 3.5 in (90 mm) and counting roughly 13 discs across makes the disc (or sphere) size about 7 mm. I hear what you are saying about the size expansion and spicules though. What excludes the Crinoid diagnosis? Couldn't the apparent spherical impressions have been disc shaped and then rounded by erosion? Forams the size of a dime... Lepidocyclina.jpg The photo is fuzzy, but crinoids wouldn't have that halo of material around them, and they would not be joined together. That joining looks like "cocci" formations commonly found when simple life forms join together to make colonies. I'm sticking with some type of planktonic cocci critter. http://www.google.com/search?q=plankton+cocci&btnG=Search&hl=en&gbv=1&tbm=isch I don't know what is the size of a dime, but i have big foraminiferas in my collection : the one that i showed in another post that is 2 cm in width and several other ones that look like tmaier's and are a little less than 2cm round. "On ne voit bien que par le coeur, l'essentiel est invisible pour les yeux." (Antoine de Saint-Exupéry) "We only well see with the heart, the essential is invisible for the eyes." In memory of Doren Link to comment Share on other sites More sharing options...
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