I recently found this rather good (for the area) and rare goniatite, probably Girtyoceras sp.
The innermost half of the living chamber has a mass of small rods which a few knowledgeable friends have suggested are faecal pellets from something that took up residence.
It's in an ironstone nodule from a Brigantian (U. Mississippian) shale in Co. Durham, N.E. England.
Fairly shallow water, with a diverse fauna of brachiopods, bivalves, bryozoa, small corals, crinoids etc., often broken up.
I haven't seen any arthropods apart from small Paladin trilobites which are quite