Canreef Aquatics Bulletin Board - Snail Hitchhiker ID's

Hi all,

I've done some Googling in an effort to determine what these creatures going for a piggy back ride on my Trochus snails are, but I'm having a bit of difficulty and would appreciate some help.

http://s15.postimg.org/on7zvrkl7/trochus.jpg

Sorry for the picture quality, I was having trouble shooting through the bowfront glass.
There is a flat oval worm-looking thing in the red circle with sort of a skirt around the edge of it. My best guess from searching was a chiton?
The one in the green box puzzles me. There's sort of an encrusted ridge along part of the outside of the snail shell, and within this ridge a fuzzy creature is living. You can sort of see the greyish bristles sticking out near the top of the box. I watched a cleaner shrimp try to catch it at one point, but it retreated and then came back out shortly after. There's also a white tentacle type thing coming out a little further down, and I have no clue if that is a separate creature or not but it seems to also be coming out of the ridge. Another one of my snails has a similar ridge with the same style fuzzy creature coming out of it. They seem to be pretty harmless (I never actually see them come out more than a couple millimeters), but hoping I could get an ID on them.
Thanks in advance for your assistance.