what might this be?

[axe_man16]

i have noticed that on the back part of the glass there is very small white spiral shaped things. i noticed a while back one on my live rock. it was about 3x the size of the ones on the glass (about 1/4" of an inch) and there is a red feather like worm that lives inside. any idea what this might be? should it be removed, doesnt seem to bother anything, but there is about 50 of them on the glass now