mhall Posted July 5, 2021 Share Posted July 5, 2021 Hi, I bought this at a flea market in McKinney, TX about 8 years ago and am trying to get it identified. The person selling it didn’t have any information on where it was found or what it is. I took it to a local rock shop recently to see if it could be ID’d. The owner is more skilled in minerals, but he thought it might be a fossil (stromatolite), and recommended I reach out to someone skilled in fossils to know for sure. Magnets do not stick to it at all. I found a small seashell attached to it, but nothing else on the outside. It’s a rounded triangular shape. Measures about 8 1/2” (32cm) tall and the base is about 7” wide by 6” deep. It weighs just a little over 16 lbs. The material in-between the fossils(?) can be scraped away pretty easily, like a sandstone. Any knowledge shared is sincerely appreciated! ! Link to comment Share on other sites More sharing options...
JohnJ Posted July 5, 2021 Share Posted July 5, 2021 Welcome to The Forum. A few close ups of the seashell and other details, as well as a view of the other side could help. 1 The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
mhall Posted July 5, 2021 Author Share Posted July 5, 2021 Here are some more pics, and a close up of the seashell. It pretty much looks the same from all sides (to my untrained eyes ) 1 Link to comment Share on other sites More sharing options...
JohnJ Posted July 5, 2021 Share Posted July 5, 2021 @DPS Ammonite @MarcoSr @minnbuckeye @Wrangellian The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
Wrangellian Posted July 6, 2021 Share Posted July 6, 2021 Well I'm not exactly an expert but since no one else has chimed in I will say it does have that stromatolite look about it. If it's younger than Devonian then it won't be a stromatoporoid, but we don't know the age, do we? I've never seen a stromatolite with a bivalve/brachiopod wedged into it. If it weren't for that I would have assumed it was from the Green River Formation (Eocene age). Anybody recognize the brach(?), and can it narrow down the age/formation? Link to comment Share on other sites More sharing options...
DPS Ammonite Posted July 6, 2021 Share Posted July 6, 2021 Could be a stromatolite. You really need to know where it came from to better assess probability. My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
FranzBernhard Posted July 6, 2021 Share Posted July 6, 2021 Could it be an accumulation of oncoids, forming an oncolite? Franz Bernhard Link to comment Share on other sites More sharing options...
DPS Ammonite Posted July 6, 2021 Share Posted July 6, 2021 (edited) 32 minutes ago, FranzBernhard said: Could it be an accumulation of oncoids, forming an oncolite? Franz Bernhard If the layered structures are roughly spherical and separate they could be oncoids which are a form of stromatolites. Maybe the poster can tell us if the are spherical. Edited July 6, 2021 by DPS Ammonite My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
Tetradium Posted July 6, 2021 Share Posted July 6, 2021 4 hours ago, Wrangellian said: Well I'm not exactly an expert but since no one else has chimed in I will say it does have that stromatolite look about it. If it's younger than Devonian then it won't be a stromatoporoid, but we don't know the age, do we? I've never seen a stromatolite with a bivalve/brachiopod wedged into it. If it weren't for that I would have assumed it was from the Green River Formation (Eocene age). Anybody recognize the brach(?), and can it narrow down the age/formation? The problem is we need the hind edge of the shell exposed. Link to comment Share on other sites More sharing options...
mhall Posted July 6, 2021 Author Share Posted July 6, 2021 Hi, I'm the poster, and I'm sorry I don't have more info. I don't know much about rocks/minerals/fossils. I purchased this from a person watching a booth for someone else and they didn't have any information on it. If I had to guess, the first pic I posted is of the top. The rock seems a little heavier than its size too. Not sure if that helps anything. I live in North Texas and so I assume since it was a local flea market, that it came from North Texas. Here are a couple of close up pics in case this helps. I've looked at hundreds of images of stromatolites and stromatoporoids on the internet and haven't seen a 'eureka' image yet. I was thinking of having it cut and polished, but wanted to make sure that wasn't a bad move before I had it done. Link to comment Share on other sites More sharing options...
MarcoSr Posted July 7, 2021 Share Posted July 7, 2021 On 7/5/2021 at 1:31 PM, JohnJ said: @DPS Ammonite @MarcoSr @minnbuckeye @Wrangellian The vast majority of stromatolites that I see on the web and that are in my personal collection are cut and polished slabs where the patterns, indicative of a stromatolite, are clearly visible in the specimen. I have not seen a stromatolite with a bivalve/brachiopod wedged into it before. So I asked Dan Damrow, who collected, cut and polished a number of the stromatolites in my collection, his opinion on this specimen. My latest book on stromatolites, Leis, Stinchcomb, Mckee, 2015, Stromatolites Ancient, Beautiful, and Earth-Altering mentions Dan Damrow specifically as "perhaps the greatest purveyor of stromatolites nationwide". The author also states "I have obtained many fine specimens from him." So I do trust Dan's opinion. This is what he said: So, I would agree with you that typical marine organisms are seldom found with stroms as stroms thrive best in a hyper saline environment. Hostile to a lot of typical organisms like the brach in the photo. But, never say never. I have seen exceptions like that one in the photograph but not commonly. And there are some things that appear to be stroms but are not. Like some corals and stromatoporoids. There are also red algaes and coralline algaes and other algal forms that do not fit the norm of classic stromatolites but sort of look the same. …….. The best is to get a general location and age. Would still like to cut a piece and see what is inside. So probably the only way to tell for sure is to cut the specimen. Marco Sr. 5 "Any day that you can fossil hunt is a great day." My family fossil website Some Of My Shark, Ray, Fish And Other Micros My Extant Shark Jaw Collection Link to comment Share on other sites More sharing options...
mhall Posted July 7, 2021 Author Share Posted July 7, 2021 @MarcoSr Thank you so much for your detective work! and Thank you to all the responders & Admin for your help! I'll have it cut in half and polished to see what shows up. I'll comeback and post a picture when that's done. Fingers crossed it's as cool looking on the inside as it is on the outside . 1 Link to comment Share on other sites More sharing options...
mhall Posted August 6, 2021 Author Share Posted August 6, 2021 Ok, it's been cut and polished and it is beautiful! Looks like fluffy black and gray clouds. Attached are some outdoor and indoor pics. Does everyone still agree with Stromatolite? 1 Link to comment Share on other sites More sharing options...
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