Ulcragyceptimol's picture


Observed: 16th February 2011 By: Ulcragyceptimol

While out walking recently, this little beauty caught my eye as it lay near to the footpath I was on, in the middle of an otherwise ploughed field. The ploughed field in question was at the top of a Chiltern Hill near Chesham, Bucks.
It looks like it's made of the same material and is the same colour as the flint nodules that are abundant in the field in which it was found.
I'd love to know what the heck it is and when it lived...

    Likely ID
    Confidence: I'm as sure as I can be.
    ID agreements (): 3 People
    • Jonathan
      iSpot team
      Jonathan’s reputation in InvertebratesJonathan’s reputation in InvertebratesJonathan’s reputation in InvertebratesJonathan’s reputation in Invertebrates
    • anonymous spotter
    • DavidNotton
      Natural History MuseumNatural History Museum
      Invertebrates expert
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anonymous spotter's picture

Assuming it is a fossil -

And not just an oddly-weathered fragment of sedimentary rock, have a browse at:
which has a good selection.

Peter Skelton's picture


Yes, I'm afraid that RogerR is on the button there (sorry to disappoint!): it's what's called a 'pseudofossil' - something that looks just like a fossil (like a segmented worm in this case), but which is of inorganic origin. Flint banding like this is not uncommon and reflects subtle layered variation in the completeness of replacement of the original chalk sediment by flint growth (taking place some time after deposition of the sediment), subsequently picked out by differential erosion on the surface of the pebble. Flint growth also often occurred selectively along old burrow-fills, which may account for the elongate shape of this pebble.

As a boy, I made several trips to the 'British Museum (Natural History)', as it then was, with my precious collections of such flint 'fossils' (...they looked to me like worms, bones, all sorts!) that I had found around my home, only to be repeatedly disappointed by the kindly experts there who patiently explained how, once again, I had been fooled by 'flint freaks'. One key is that you won't find any internal structure to them, other than just bland flint - which, as a chemical replacement of whatever was previously there (usually chalk) grew in response to subtle variations in porosity and pH, so adopting all sorts of strange and misleading shapes. 'Real' body fossils of once-living organisms often show some vestige of original internal structure and/or external features more diagnostic of particular groups of organisms (such as the five-fold radial symmetry of many echinoderms). Having said all that, I should add that you can also find nice specimens of body fossils incorporated in flint nodules; sponges are especially common.

But do keep up the fossil-hunting!

Ulcragyceptimol's picture


Well, thank you guys. I'm slightly disappointed it's not a new phylum of previously unknown invertebrates, but I'm very happy to know at last what it is. Thank you for your expertise.