Description

Also known as Octocoral, Sea Feather, Sea Finger, Sea Quill.

Found in shallow waters, on soft sandy bottoms, often withdrawing into the substrate during the day.
They feed on plankton drifting past.
Length - 60cm
Depth - 10-300m
Widespread Indo-Pacific

Sea pens have a large central axial polyp with an internal calcareous axis. Half of the sea pen is buried as an anchoring root, the upper half reaches into the water to feed on plankton.
Sea Pens are often home to commensal crustaceans.
A few sea pens are found in shallow waters, but most are found in deeper waters where they are less likely to be disturbed. (edit) Ref: https://en.wikipedia.org/wiki/Cerianthus_filiformis