Are sea pens invetebrates

Yes, sea pens are invertebrates. They belong to the phylum Cnidaria and are closely related to corals and jellyfish. Sea pens are colonial organisms, typically found in shallow ocean waters, and have a structure that resembles a quill pen, which is where they get their name. They are anchored to the seabed by a root-like structure and can retract into their protective casing when disturbed.