White feather duster\worm looking things on rock?

Hi, does anyone know what these little white feather duster type of things are? They're floating in the water column and sticking to the glass in the back corner of my tank that doesn't get much flow. They're white, have heads such as a feather duster, but chubby white bodies? I don't notice any retraction, in terms of a feather duster going back in it's tube. I've had this tank for several months now and haven't added anything new, but this is a new development.











I've been battling with Dino's lately, as you can see from the pictures.