A unique creature of the seafloor - the sea pen resembles an old-fashioned quill pen.
Each sea pen is a colony of polyps. The primary polyp loses its tentacles and becomes the stalk of the sea pen, with a bulb at the base which anchors the sea pen to the substrate. The various secondary polyps form the sea pen’s “branches” and have specialised functions. These polyps have 8 tentacles which means sea pens are octocorals 🌊