So I am still fairly new to this hobby, and noticed that on one of my rocks, I have several worm looking things.  The look like they build their home using sand particles creating a tube sort of thing.  They also stick out their inch long clear tentacles waving them around.  Should I be concerned about them?  Are they bad?
This might be a separate note, but every time I do a water change, i have these tube looking things (almost like very small feather duster tubes) that secrete what looks like a slime or mucus.  It eventually goes away, but when I am done changing the water, I have what looks like spiders webs all over my rock.  Are these two things related?
Thanks for your help, like I said, i am new and do not have the experience that you all have.
