A stressed out orange sea pen (Ptilosarcus gurneyi) is hunkered down and waiting for a large diamondback nudibranch to take a bite.
The orange sea pen was named after an old-fashioned quill pen which it resembles. Each sea pen is a colony of polyps (small anemone-like individuals) working together for the survival of the whole. Each polyp is specialized and one even develops into a rigid central tall stock that supports the other polyps and provides an anchor to the ocean floor. The orange sea pen grows to around 18 inches (48 cm) tall, with a range from northern Alaska to northern Mexico.