Dr. Wood said:
Normally these occur in soil and sediment, especially at the bottom and edges of polluted streams. In the photo they have apparently entered a pipeline somehow, and in the absence of soil they are coiling around each other
Seems to be a crack in the pipe at those locations, so they may actually be "in soil and sediment" and they are located "especially at the bottom and edge of polluted streams", i.e., that sewer pipe.
No, I would not want to see that when scoping out a sewer pipe!
