That could very well have been involved as well. I was referring to this:
“Just as modern biologists do when doing anatomical studies, researchers put fragments from the broken bone in a mild acid solution to strip away mineral deposits. What was left floating in the solution was thin, stretchy material threaded with what looked like blood vessels.”
...which when analyzed turned out to be biofilm - e.g. algal/bacterial residue that had been deposited on within the bedding planes of the rocky outcrop where the fossil was found.
And now that there has been time to examine it more closely, and independent studies have also been conducted on those samples, has it turned out to be blood vessels?