On my last dive/ snorkel trip to the Galapagos I was filming a Flightless Cormorant. We were snorkeling in about 6' of water and we were watching the aquatic bird hunt along the rocky sea floor. The bird found a banded, "worm-like" creature and was trying to pull it out of the rocks. It worked at this for 10 or 15 minutes before giving up. I am enclosing a link to a video I made of the event. I am hoping somebody can identify the worm-like creature. You will notice that the creature is very long - at one point we saw about 10 to 12 feet of it exposed and we never saw one end (presumably the head.) The creature was about half and inch wide and only a few millimeters thick (at least when it was stretched out). The creature was stretchy. You can see it elongate and compress in the video as the bird tugs on it and then it escapes and tries to pull back into the rocks. In my mind that means to me that this is not a vertebrate. I don't think anything with a spine (like an eel or snake) can stretch and compress like that. What is this thing?