Interesting trace fossils... or pseudofossils! I do wonder whether these are concretionary growths around a single vertical burrow, instead of cnidarian resting traces; they seem too 3-D for that interpretation. The lobes on the larger one are also very irregular, which would fit with mineral... if you're willing to cut one in half an polish it, you might well find some interesting things.
The Coniston ones are rather nice orthocone nautiloids.
Aye, I misread 'medusiform' for 'medusoid!' - sorry about that. There is a lot of ambiguity over trace- versus pseudofossil in these things. Seilacher (sadly he died earlier this year) was a bit of a maverick genius in many ways. I got an insight into his thinking by staying with him for a few weeks, and he basically worked on constructional engineering principles, rather than biological or chemical ones. Not saying he's wrong, but just that it's worth bearing in mind that his interpretations frequently pushed the boundaries a bit. What little I can find on Palaeosemaeostoma is sadly in Russian:
But yes, it does look identical, whatever it is! I'd definitely like to see the internal structure, which should let us work it out.
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