Does anyone recognise this?
I noticed it when scanning photos of a recently cut and polished piece of Frosterley "Marble" from Weardale, Co. Durham, UK. (upper Mississippian, Pendleian).
It shows in section as a rod about 5mm long, with perforations, central ridge and a fine reticulate pattern. My first thought was a Fenestella fragment but it doesn't look regular enough and I can find no mention of the reticulate structure. Also, I've never seen bryozoans in this part of the limestone though they occur at other levels.
Now I'm wondering about a dasycladacean alga - some look vaguely similar but all the Carboniferous ones I can find references to look simpler and fuzzier.
Scale bar is 1cm, divisions are 1mm
Contrast enhanced
In context, showing ghostly appearance amongst the corals