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235 Views 3 Replies Last post: Jun 25, 2014 3:07 PM by MikeHardman RSS
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Jun 25, 2014 10:44 AM

A sponge fossil?

I spotted this in the gravel in the front garden of my Mother's neighbour in Romsey, Hampshire.  I have no idea where the gravel originated.

 

Looking at other postings here and images on the InterWeb, I'm pretty certain this is a Cretaceous sponge fossil, but I'd be grateful for authoritative confirmation.

 

If so, is it possible to identify the species?

 

Thanks.

 

John

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    Jun 25, 2014 11:38 AM (in response to gladtobegrey)
    Re: A sponge fossil?

    John,

     

    Yes, it is a sponge, but it is difficult to ID as far as species.

     

    The gravel is quite likely to be derived from the chalk (quite possibly via erosion, redeposition and quarrying), hence a Cretaceous age is very likely. And sponges are one of the most common fossils of the flints in the chalk. From its age and spherical shape, I would guess it might be Porosphaera, of which some species are mentioned here - http://www.cretaceous.de/Porosphaera.html

     

    They come up for ID/discusion on NaturePlus now and them, eg.

    - http://www.nhm.ac.uk/natureplus/thread/4367?decorator=print&displayFullThread=true

     

    Mike

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      • Currently Being Moderated
        Jun 25, 2014 3:07 PM (in response to gladtobegrey)
        Re: A sponge fossil?

        In this sort of thing, there's going to be a fair amount of opinion rather than fact!

         

        My take on the 'polar caps' is that they represent the remaining original surface of the fossil - the equatorial areas having been eroded away.

         

        Mike

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