This is a crinoid, an animal vaguely related to starfish, sea urchins and sand dollars. They are not extinct, but they are not nearly as common as they used to be. There was a time when the bottom of the continental shelf was teaming with these things, now they seem to be mostly restricted to hyper saline environments. Below I have a reconstruction.
Once again this is an animal, it moves using a water vascular system, it can pump water in and out if it's various parts and when it does so it moves. In graduate school I was once caught in an argument between two professors about whether or not the water vascular system extends all the way to the bottom of the animal. I knew enough to keep my mouth shut. (I just hmmmmed and nodded a lot)
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