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WILLUS240
my daughter and I found this on our morning walk. Any idea what it is? My first thoughts are a portion of a pelvic bone.  20200524_151805.jpg  20200524_151758.jpg  20200524_151747.jpg  20200524_151722.jpg  20200524_151711.jpg 
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Barrow Museum
Not bone, I am afraid.  But what you have found is the flint-infill of a burrow gallery, created by a small shrimp-like crustacean a few decametres below the Cretaceous sea floo,r around 80-90 million years ago.  You probably know that flint is found in layers of nodules in the Cretaceous Chalk (of which plenty around Cambridge). The source of the flint, which is essentially quartz, or Silica,SiO2, is believed to have been sponge spicules, disaggregated and then dissolved at a shallow depth below the sea floor and then reprecipitated around some nucleus.  Sometimes this might be a shell, such as a sea urchin.  But burrows were often the host for the redeposited silica, which replaced the chalk infill and then grew a bit more as well.

As it is not an actual body fossil, but the mark of some biologica activity, we call these trace fossils.
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Gary W
Yes a flint nodule
Gary
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