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Clashach
Hello
       With the lockdown I decided to investigate a pyritised ammonite block collected at Sandsend many years ago.

The block contains 4 or 5 (maybe more) ammonites of varying scales, a few less than a few mm across but what intrigues me is the feature on one side of the block.  I can't decide if it's a fossil or some sort of diagenetic feature, on one photograph you will see a very small ammonite ( to the left of the 1p coin) which seems to be underneath the feature ?

I've also included a photo of a "cross-section" through a broken off piece but can't figure out what the tube features are.  Size of the tubes maybe 2mm across.

Any help much appreciated, thanks. Click image for larger version - Name: DSC04942.jpg, Views: 67, Size: 772.38 KB Click image for larger version - Name: IMG_5859.jpg, Views: 68, Size: 630.12 KB Click image for larger version - Name: IMG_5852.jpg, Views: 62, Size: 431.31 KB Click image for larger version - Name: IMG_5838.jpg, Views: 62, Size: 345.29 KB
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Elbert
Hello, this is a partial ammonite: Phylloceras, with some smaller ammonites washed in the bodychamber. The ridges are the shell ornamentation of the Phylloceras of wich there is a partial phragmocone attached; the phragmocone is the chambered part of the ammonite shell.
Does this anwers your questions?

greets, Bert
the search is as valuable as the finds...
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Clashach
Bert,     
     Thanks for your reply.  Does that mean I've got some 2-3mm sized ammonites and one which would be 2-3ft in diameter with a small portion of it's body showing as the larger fluting marks  ?
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Elbert
Hello, these ammonites in the bodychamber are not the same species as the Phylloceras; from what I can see, I would say they are Dactylioceras athleticum and it is not uncommon to find these together with baby ammonites of the same species. 

greets, Bert
the search is as valuable as the finds...
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Elbert
Hello, the "fluting marks" are part of the normal shellstructure of  Phylloceras; if you google Phylloceras heterophylum on pictures, you`ll see what I mean.

greets, Bert
the search is as valuable as the finds...
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Clashach
Bert,     Thanks for the info, I've some reading to do !  Cheers
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