twilight.amoeba Posted August 29, 2008 Share Posted August 29, 2008 I recently found this whilst scouring the beach at Gileston, South Wales, UK. The foreshore at Gileston is full of Jurassic Boulders, I find that many of these contain shells and ammonites. There are hundreds of Gryphaea by the shore too. However, I found something very unusual today: It is so bizarrely realistic I first thought it was a hoax or piece of tired dog poo, but then I realised it's made of stone. Any help identifying this is greatly appreciated! Link to comment Share on other sites More sharing options...
Metopocetus Posted August 29, 2008 Share Posted August 29, 2008 Those would be molds from shells. The matrix hardened and the shell disappeared...leaving you with what you have there. Link to comment Share on other sites More sharing options...
Bill Posted August 29, 2008 Share Posted August 29, 2008 Hi, Do we call you twilight or amoeba It's an internal cast of a Gastropod, without the shell, which would have had/or not, some kind of ornamentation, it is nigh impossible to id. KOF, Bill. Welcome to the forum, all new members www.ukfossils check it out. Link to comment Share on other sites More sharing options...
twilight.amoeba Posted August 29, 2008 Author Share Posted August 29, 2008 Those would be molds from shells. The matrix hardened and the shell disappeared...leaving you with what you have there. Oh, that's fascinating! Thanks!. Still really looks like a poo though Link to comment Share on other sites More sharing options...
twilight.amoeba Posted August 29, 2008 Author Share Posted August 29, 2008 Hi,Do we call you twilight or amoeba It's an internal cast of a Gastropod, without the shell, which would have had/or not, some kind of ornamentation, it is nigh impossible to id. Thanks very much for replying. Do you know why there seems to be some sort of different mineral in-between the swirls? I think its fascinating that an internal cast could survive. Twilight or Amoeba is fine. Link to comment Share on other sites More sharing options...
Bill Posted August 29, 2008 Share Posted August 29, 2008 It looks like there may be decaying, (rusty), Pyrite on the specimen. Pyrite is quite common on/in fossils. The internal cast is caused by the shell getting filled with mud, clay etc which in turn hardens. The shell may have been dissolved by sulphuric acid, a by-product of the decaying Pyrite, which was in and around the original shell. Abrasion caused by wave action/gravel/sand, can also remove the softer shell. KOF, Bill. Welcome to the forum, all new members www.ukfossils check it out. Link to comment Share on other sites More sharing options...
Guest solius symbiosus Posted August 29, 2008 Share Posted August 29, 2008 A lot of molluscs secrete aragonite; which is an unstable polymorph of CaCO3. Hence, the dissolution of shell material. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now