Taylor, P.D. & Vinn, O. 2006. Convergent morphology in small spiral worm tubes ("Spirorbis") and its palaeoenvironmental implications. Journal of the Geological Society, London 163: 225-228.
Many new papers have been published on microconchids recently and there is consensus on that Spirorbis is not known before the Jurassic. What you have here are lophophorate tentaculitoids - microconchids, only superficially similar to annelid Spirorbis and described as such in older literature.
Carboniferous examples I co-authored: