My mother found this and sent it to me (as is often the case with articles I read now a days).
It actually kinda cool if you can look past the grotesqueness of the videos.

[link]

It looks so gross because the masses are so large (probably only a few centimeters I'm guessing) and the worms themselves are relatively small (at least in diameter; think they can be a centimeter in length of more... honestly I'm not entirely sure because I've never measured them).
THey make a living feeding on detritus, digesting the bacteria in the materials they ingest.