Yet Another Mystery Thingy For You To Identify

This evening Crox Minor came home from school and turned out the contents of her pockets. Among the detritus was this object, loaned her by one of her science teachers, a Dr B. B. of Cromer. I think it’s a fossil egg of some sort. I am not aware of the provenance – the object is all I have to go on. At first sight it looks like an ill-used conker, and is indeed about the same size and shape.

However, beneath the thin brown rind there is what looks like the ornament that the inside of an eggshell might leave. Any takers?


I think that’s a tyrannosaur’s left testicle an oeuf.

About cromercrox

Cromercrox is a recovering palaeontologist, author and editor who lists his recreations as writing, beachcombing, playing hard rock organ, supporting Norwich City FC and falling asleep.
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18 Responses to Yet Another Mystery Thingy For You To Identify

  1. Thomas Down says:

    Always hard to tell by photograph but looks metallic to me. Worth measuring the density?

    The tape measure suggests its a bit big to be a musket ball, but I’d be thinking along those lines…

    • cromercrox says:

      Prompted by your comment, I calculated its volume, which was around 33.5 cubic cm, assuming it was spherical and had a radius of 2cm. It weighs 79g. This gives a density of 2.35 g/cm3. This is much less dense than iron (7.87 g/cm3) or ferric oxide (5g/cm3 or thereabouts). And it does not appear to be magnetic.

      • Thomas Down says:

        Okay, that seems to rule out any credible metallic option (barring the remote possibility that it’s hollow — seems unlikely!). Also many minerals (Goethite 3.3-4.3g/cm^3). 2.35 is about the density of flint. Fossil of some kind does sound plausible.

  2. greg laden says:


    • cromercrox says:

      I don’t think so. We have specimens of what looks like goethite picked up in France on holiday, and this thingy doesn’t look like those.

  3. Steve Caplan says:

    Looks a little like the mandarin orange I found behind the sofa, probably a year old. Does that count as a fossil?

  4. I have two guesses for you:

    1) fossilized nut or seed, rather than an egg
    2) some naturally occurring mineral form, like a geode perhaps.

    When I was about 7 years old, I wanted to be a geologist, but my knowledge hasn’t progressed much since then. I’m better at dead-things-found-washed-up-on-the-beach, but only marginally.

  5. John the Plumber says:

    Bacup is a stone guarry area, mainly hard sandstone to the south but shale and coal to the north. The paving flags in Trafalgar square purportedly came from Bacup. I’ve never found a fossil in the local sand stone but often find what must be ‘filled bubbles’ – particularly in some of the softer sand stone. Some look awfully like almond nuts and often I go down the route ‘Hey look what I’ve found’ – then I go, hang on a minute, there is nothing else in this particular type of stone to say that there was any life about when it was laid down, so its just a boring geological effect. – Hope yours turns out to be more exciting.

    On the other side of Bacup, in the shale measures they arrived at a layer of fossilied tree stumps estimated to be 300,000 yrs old. The qurry owner, not one for publicity, did quiet research and an Ausralaian scientist recorded the site before it was filled in when the quarry moved on. – I have a chunk of fossil tree stump sitting next to my desk. I’m very proud of it. I’ll try to email you a photo if my computer skills manage it.

    Any way – now you’ve tried a few ways to make sense of your nut egg or musket ball, why not try the scientific appraoach – hit it with a hammer and chisel to see what’s inside.

    Of course it does resemble the early earth before the continents were as they are now. Perhaps it’s an ancient space tourist’s pocket map that he (or she) dropped before going home. – Or even a dessicated planet from another universe. – You guys just lack imagination.

  6. alejandro says:

    Is a simple stone.

  7. Mandy says:

    It’s a beach worn marcasite nodule ?

    • cromercrox says:

      Hmmm. It’s a possibility but would marcasite survive long enough to be beach-worn?

  8. Cath@VWXYNot? says:

    Looks like the larval form of the lesser spotted haggis. X-ray it to see if you can assess its leg-lengths.

    • John the Plumber says:

      What do you gamble on Cath, a clockwise or an anticlockwise haggis larvae fossil? – though definitely I agree is stone.

      • Cath@VWXYNot? says:

        well, judging by the location of the dimple in the middle of the object in the first photo, I’d say that it’s probably the much rarer clockwise form of the species.

        I did my PhD in Glasgow. I know these things.

  9. chezjake says:

    Looks like the pit from an avocado — probably quite dessicated.

  10. John Gilbey says:

    Prof Trellis’ care worker suggests that – while the other suggestions are appealing – the object is a concretion… Google has some nice images under that search term which look rather similar… Tempting to saw it in half – if it wasn’t a loan… :-)

  11. Ken says:

    I was going to second the avocado pit suggestion, but it must have been a pretty huge avocado. My second choice is an alien embryonic pod. Place it in water, feed it after midnight, etc.

  12. Lynn says:

    A very large fossilized Hershey’s Whopper Malted Milk Ball