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Helicoprion Shark Fossil?


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Good afternoon, 

I would like to start off with saying that I know very little about fossils and Geology so please excuse me if I make any errors or misstatements. Recently I purchased approximately 10 cubic yards of rock from a local business to use for landscaping around my property. The business has claimed that the rocks they sold me were excavated from in or near the banks of the Snake River in Southern Idaho. I unfortunately do not have a more exact location but I would be willing to possibly follow up with the business if more information is needed. With the help of some friends we were able to determine that scattered throughout the 10 yards of rock I received were Agates, Jasper, Opal, Amber, Star Garnets, and small fish and crustacean fossils with some even appearing to be in a preserved state encased in a soft yellow translucent amber. Knowing some of the types of rocks I received, the general location of excavation, and a brief history of rare fossils that are found within Idaho I was stunned when I came across the specimen pictured below. Most notably the spiral tooth-like feature is what drew me to this rock and made me take a closer look. There are very distinctive features that appear to be eye holes, nostrils, gills and of course the famous spiral tooth pattern. The internal structure looking through the eye is a completely opaque white substance that resembles a mix of opal, amber, and other silica material. The silica based specimen appears to be sitting on top of a hard rock stone. Sunk into the very bottom of this stone is a 2nd spiraling tooth-like feature which I only guess could be the other set of teeth.  After coming across this rock and with the little stated knowledge that I have on these subjects I took to the internet to attempt to research Helicoprion fossils and in general shark fossils. As many of you are probably already aware besides teeth it is very rare to find any fossilized portion of a shark of any species let alone a possible intact skull from one of the rarest sharks out there. The overall size of the specimen is also a little concerning as my understanding is that the Helicoprion shark was a rather large shark and was likely somewhere between 3-5 meters at full growth. After doing the research on whats out there and based off of what I already know I still remain rather skeptical that this is what I'm claiming it to be but at the same time remain hopeful that this is a fossil of some sort as I am having trouble coming up with an explanation for the content that this rock is made of among others in the rock pile and for a reasonable natural explanation for spiraling patterns. This is 1 of 3 rocks that I've found thus far with spiraling teeth-like features. The other 2 are made of similar material, resemble some similar structures, and share distinctive features other than the spiral such as eye holes, nostrils, jaw lines, and ect. The major difference between the 3 is the specimen that is pictured here is larger, more intact, and displays the most features. I appreciate any feedback that I can get because of the pandemic college campuses are closed and it has made it hard to get in contact with people who could possibly help me. I would like to have as much knowledge on what this possibly is before jumping in the car and driving to the nearest Natural History Museum which is over 3 hours away from me. I would hate to do something like that if this is only just a "cool" rock. I have many more pictures if needed displaying all of the features mentioned and many more as well as pictures of other specimen found in the same rock pile just let me know if they are needed or wanted and I can message them or make another post with them.              


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Welcome to the forum! :)


I"m sorry, but I think you have found a suggestively shaped rock. It is possible that it is a very worn piece of coral. 

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Not a tooth whorl or a skull I'm afraid. This is purely geological I'd say. Mother nature sure does make some interesting shapes in rocks. Here is a picture of a real tooth whorl, they are highly detailed and distinct:


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Interesting shapes and cool keepsakes but agree with the others geologic in orgin.

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