Red Sea Fingers, Alcyonium glomeratum, are a colonial soft coral and in the photograph you will be able to see the individual coral polyps projecting into the water to trap passing plankton. If disturbed - or perhaps during periods when the tide is not running - the polyps withdraw and the body matrix of the colony shrinks. The section of the animal at the bottom right illustrates how this looks.
Not a common species and only found in certain locations on south and west coasts where it seems to prefer deeper, overhung situations. The body matrix may be either red or a dull yellow.