I have now looked closely at two segments of this material i excavated from Mercia mudstone at Stainsby beck Thornaby on Tees. ( As reported in earlier posts.)
I have found at least four separate mineral lined tubes with what look like carefully placed side pieces.
These could as far as i know the only fossil material ever found in the Mercia mudstone in this area.
The mineral lined half tubes can be seen in the centre of the image above, and just below left.
