The Phosphorescent Sea Pen is a deep reddish pink sea creature that has a long thick stem with feathery-looking branches. It has the name ‘Sea Pen’ because it looks like an old-fashioned pen called a ‘quill’ which was made out of a bird’s feather. It can be found in the North Sea in waters as deep as ten to a hundred metres where it anchors itself firmly into muddy, sandy or gravel seabeds.

The Phosphorescent Sea Pen is made up of different ‘polyps’. Polyps are small organisms that have a mouth and tentacles and this group of polyps forms a colony. The colony has a primary polyp that takes the form of a fleshy-looking, long thick stem which loses its tentacles and forms a bulbous root at the base. The stem is around forty centimetres tall and has lots of branches on either side. The branches are formed by white coloured secondary polyps which can be seen in rows all along the branches.

The Phosphorescent Sea Pen also has its name because  it  is ‘phosphorescent’.  This means it can give off brilliant flashes and pulses of blue-green light if it is gently touched. The light comes from the polyps which are connected to a network of nerves.