I just noticed these critters a few days ago. It seems that they are tube dwelling. The tube looks like a feather duster tube. It's only about an inch long and and little more than an 1/4th of an inch in diameter . The thing that bobs in and out of the tube appears much smaller than the tube about a 1/16th of an inch in diameter. It sort looks like a worm with black and white stripes running the length of the body, I've only seen about a 1/2 inch of the body, with whiskers on the tip. It only comes out when something gets near the opening of the tube and then quickly retreats. I don't have a pic because it's only out for a brief second. Any ideas?