Skip navigation
8026 Views 5 Replies Last post: Mar 7, 2011 5:24 PM by Luanne - former Museum ID team member RSS
Currently Being Moderated

Apr 20, 2011 1:30 PM

Answered - Sponge fossil nodule, not fossil egg

My Grandpa passed away last year and amongst the bits he passed on were some fossils, I find this one interesting as it was simply labelled Dinosaur egg. Unfortunately this is all the information I have, other than he lived in Prescott valley in Arizona USA. Apparently he regularly picked up interesting rocks and arrow heads during his walks.


Please could someone take a look at the photos & let me know if this is likely to be an egg, gastric stone or just a round pebble. There appears to be a hole in the top with fragments inside.


Many thanks



  • Currently Being Moderated
    Jan 30, 2011 4:18 AM (in response to fossilfan)
    Re: Dino egg or round rock?



    Looking at the 2nd picture of your egg shaped rock it is easy to see why it has the appearance of some kind of fossilised egg.


    I think it's likley to be a "Geode" which is a rounded hollow rock, they are often have crystal substances on the inside such as agate or quartz.


    Here is a link to Wikimedia where I found the attached picture.



    I hope this helps.

    • Report Abuse
      • Currently Being Moderated
        Feb 5, 2011 5:25 PM (in response to fossilfan)
        Re: Dino egg or round rock?

        Hi fossilfan


        Looking at picture 3 there appears to be quite a cavity which you may be able to clean up enough to establish what is inside before cracking it open, so to speak. The same picture also shows the thickness of what would be the egg shell, so if it were originally an egg whatever was inside would have needed to be extremely powerful to break it's way out. That is why I believe your egg is a geode, which in itself is an extremely unusual item.


        I'm no expert, just someone who is very interested in fossils and artifacts. I hope the reasoning behind my explanation has helped.



        • Report Abuse
  • Currently Being Moderated
    Feb 25, 2011 10:55 AM (in response to fossilfan)
    Re: Dino egg or round rock?

    HI! I think that it is some sort of garasic stone because of the shape. How big is the hole and how wopuld you describe the small fragments?Are there any parts of fossilised stone in side?

    • Report Abuse
  • Currently Being Moderated
    Mar 7, 2011 5:24 PM (in response to fossilfan)
    Re: Dino egg or round rock?

    Hi there,

    I wanted to be sure on this, so I showed the pictures to some experts in the palaeontology department who confirmed that sadly it is not a fossil egg. They both said the hollow, ovate structure and appearance of the inside looks like a sponge fossil within a nodule. Round nodules often form around sponges, and the sponge often breaks down inside to leave an appearance like this is the hollow centre.

    Hope this helps,


    • Report Abuse

More Like This

  • Retrieving data ...

Bookmarked by (0)

What the symbols mean

  • "correct" answer available
  • "helpful" answer