ID please

[Alberta-newb]

I've done quite a lot of searching but haven't found an ID on this other than references to some sort of "tube polyp" or "stick polyp" which isn't too scientific.



The tubes themselves are translucent and fairly rigid and when disturbed, the polyps(?) will quickly retract into them. When I first saw them a couple of months ago the coloration was a pale yellow/brown but have changed to a bright lime green color that really shows well under actinic (off for the photo). Each one is about 2-3mm across when open.

I would imagine this stuff is fairly common as it was a hitchiker and is showing up on a couple of pieces.. would like to know a little more about them.

Thanks,

Francis