Sea Pen

This was a rather large Sea Pen, the part that was exposed from the sandy bottom was around 30 cm in length/height. They are called Sea Pen as they resembles the quill pens of the olden days. They can retract themselves into the sandy bottom when disturbed but the bigger specimens seems not to be able to retract completely. Sea Pens are usually host to variety of Crustaceans (Shrimps & Crabs) that lives between the segments.

They are colonial marine cnidarians belonging to the order Pennatulacea. There are 16 families within the order; they are thought to have a cosmopolitan distribution in tropical and temperate waters worldwide. Sea pens are grouped with the octocorals ("soft corals"), together with sea whips or gorgonians.

Although named after their feather-like appearance reminiscent of antique quill pens, only sea pen species belonging to the suborder Subselliflorae live up to the comparison. Those belonging to the much larger suborder Sessiliflorae lack feathery structures and grow in club-like or radiating forms. The latter suborder includes what are commonly known as sea pansies.

The earliest accepted fossils are known from the Cambrian-aged Burgess Shale (Thaumaptilon). Similar fossils from the Ediacaran (ala Charnia) may represent the dawn of sea pens. Precisely what these early fossils are, however, is not decided.