Ashes in tank?

[b_ball12_99]

In my tank I have what looks like ashes on my rocks but mostly has the bottom of some of them. Is something digging out my rocks or crushing my cc into this dust looking substance? I have seen a yellow worm with black vertical stipes on the center of its back, never got an ID on it. Also have a few red worms with whiskers that have pulled cc up to their rock entrances and have made tunnels with the cc that goes to the top of the cc and around the tank, neat work from them, makes me wonder how the got the cc to stick. Any ideas on what is making the ashes/dust or any ID's on the 2 different types of worms?

 

[b_ball12_99]

My best guess is that it has to be worms. It was in there before I added my percula clowns. They yellow worm was at least 6" long with 3-4 black strips going up and down its back. The tunnel making red worms are bright red with catfish like whiskers. They have some black mixed in them. If I could see one I could make a better description but its been awhile since I've seen them since they now have tunnels.