Dead man's fingers  (Alcyonium digitatum)

Cilia: Microscopic hair-like appendages found on the surface of cells or single-celled organisms. In some species, cilia are used in locomotion or in feeding; by rhythmically contracting they can generate currents in the surrounding fluid.
Hermaphroditic: Possessing both male and female sex organs.
Larvae: Stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
Plankton: Aquatic organisms that drift with water movements; may be either phytoplankton (plants), or zooplankton (animals).
Polyp: Typically sedentary soft-bodied component of cnidaria (corals, sea pens etc), which comprise of a trunk that is fixed at the base; the mouth is placed at the opposite end of the trunk, and is surrounded by tentacles.

1. Budd, G.C. (2001) Alcyonium digitatum. Dead man's fingers. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme. [On-line]. Plymouth: Marine Biological Association of the United Kingdom. (November, 2003)
   http://www.marlin.ac.uk/species/Alcyoniumdigitatum.htm
   
2. Fish, J.D. and Fish, S. (1989) A student's guide to the seashore. Unwin Hyman Ltd., London.
   
3. Gibson, R., Hextall, B. and Rogers, A. (2001) Photographic Guide to the Sea & Shore Life of Britain and North-west Europe. Oxford University Press, Oxford.