Animal, vegetable, or mineral? Help with finds from Charmouth, Dorset, UK

[citronkitten]

Greetings,

 

I have 4 pieces from Charmouth on the Jurassic Coast in Dorset that I am having trouble identifying. They were found during a fossil hunt led by the Charmouth Heritage Coast Center when they brought us to a stretch of beach between the Centre and Black Ven to the west.  We would have been looking through the Black Ven Mudstone 'Shales with Beef' portion on the foreshore, which is from the Jurassic (no surprise, given the name of the area) period. 

 

Here are my best guesses:

 

A = rolled bone, B = crinoid stem or coral, C = multiple bivalves and ammonite impression in matrix, D (the unlabelled one) = wood

 

As always, corrections/confirmations/clarifications are much appreciated, as is your time for reading my post!

Edited February 19 by citronkitten
order of images

[Lone Hunter]

I don't think there's such a thing as rolled bone, the first two look like infilled burrows to me.  That's a nice little ammonite not just an impression from what I can tell and last one does look like wood though picture is not so clear.

[citronkitten]

Thank you @Lone Hunter for your response!  Some updates:

 

A = Was identified immediately and confidently on the Dorset Fossil Hunters facebook group as a "carbon electrode from an old dry cell battery", which is why I couldn't find anything like it in any fossil images. As far as the 'rolled bone' term, I got it from this website: https://ukfossils.co.uk/2016/06/17/compton-bay/rolled-dinosaur-bone-from-compton-bay/ . I've been reading through a number of pages and it seems to be used fairly frequently. I'm not sure if there's a more technical version of the term, though. 

 

B = I have now updated in my album, thank you.

 

C = Unfortunately the ammonite has mostly popped out with only the outermost ring remaining in the matrix, but very cleanly. I've attached some more photos of that as well as some detail of the surrounding shells. I applied clear nail polish on them to help with the shine and prevent flaking; I've been reading that a PVA solution might be better? 

 

Cheers!

 

 

 

Edited February 20 by citronkitten
realized how to change photo size in post