Identifying a Mysterious Rock: Seeking Help and Answers

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The discussion revolves around identifying a rock that a user believes might be a nest or an egg. Initial suggestions point to the possibility of dinosaur eggs, but further analysis reveals that the rock likely contains fossilized bi-valve sea shells within a water-worn pebble. The context of the rock's location near St. John's, Arizona, and its proximity to the Petrified Forest National Park suggests it could be related to fossil reptile eggs, though the evidence does not convincingly support this. The conversation emphasizes the importance of context in rock identification, such as the geological history of the area and the characteristics of the specimens. Ultimately, while the rocks are intriguing, they may hold more value as a mystery than as definitive fossil evidence.
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Can anyone help me identify this rock a friend of mine said it might be a nest of some sort or an egg curious to know if anybody has any ideas on what it is thank you
 

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Thankyou I think you are correct I found the link helpful and very interesting
 
Do you I think these are dino eggs
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Lori Fenton said:
Do you I think these are dino eggs
Unfortunately not. The first two pix in post #4 show a fossil bi-valve sea shell in a water worn pebble. The sea shell filled with silt, which has survived, but most of the shell material has been weathered away due to higher carbonate content. Can you see the internal muscle attachments on the filling? There are many other smaller fossils in that pebble.
 
I don't quite see the seashell thing these two rocks were found together in northern Arizona around st. John's area I believe petrified eggs maybe I don't know you're curious though they look so they're turning to Agate Maybe but then again I'm not an expert just thought they were cool
 
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  • #10
Please identify rocks with a number that stays with the specimen in all photos.
Post #9, top rock, could be many curved sections of fossil sea shells showing on the surface of a water worn pebble.
Post #9, bottom rock, onion skin weathering, ex-foliation, maybe from a soil or exposed to sun and frost.

Context is everything. How did they get to where you found them? Were these found with other rounded pebbles in a stream bed or dug out of boulder clay? Were they part of the local bedrock? Did they come from glacial outwash? What part of the valley?
 
  • #11
Those rocks were found somewhere around Saint John Arizona I'm not surface of the location because a friend of mine gave them to me just before he passed away so that's all I know about them sorry
I will definitely take more care in my pictures and identifying each side of the specimens make it easier to identify thank you for the advice
 
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  • #12
20 km up the road from St Johns are the rocks of the Petrified Forest National Park.
https://en.wikipedia.org/wiki/Petrified_Forest_National_Park#Fossils

The proximity to Triassic formations suggests fossil reptile eggs may be present in the vicinity. The pictures do not convince me that you have fossil eggs, but rounded rocks in the vicinity could be early dinosaur or crocodile eggs. It makes a good story and encourages a healthy interest in geology.
 
  • #13
So you think it's worth a trip to the university to have them looked at a bit closer then
 
  • #14
Lori Fenton said:
So you think it's worth a trip to the university to have them looked at a bit closer then
Probably not. On the balance of probabilities, they are worth more as a mystery than as a certainty.
 
  • #15
Ok thanks
 
  • #16
Lori Fenton said:
I don't quite see the seashell thing

shell in mudstone.JPG


the shell would have curved right over the top of that arrowed yellow arrowed area but it have now worn away
Bits of shell can still be seen along the red dotted line and there will still be more of the shell on the insideDave
 
  • #17
Lori Fenton said:
Can anyone help me identify this rock a friend of mine said it might be a nest of some sort or an egg curious to know if anybody has any ideas on what it is thank you
Lori Fenton said:
Can anyone help me identify this rock a friend of mine said it might be a nest of some sort or an egg curious to know if anybody has any ideas on what it is thank you
I think this is a Septarian Nodule, although not as pretty as some
 
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