Although it may be hard to tell from just images alone, this is a very weird creature. From photos it resembles an aquatic plant but they are in fact marine animals. They are Crinoids, and they live in depths as great as 9,000 meters. When they are adults, they are attached to the sea bottom by a stalk and are commonly called sea lilies. When they are unstalked and out swimming, they are called feather stars. The majority of Crinoids are free-swimming and have only a vestigial stalk.
Crinoids feed by filtering small particles of food from the sea water with their feather like arms. The tube feet are covered with a sticky mucus that traps food that floats past. They then use the arms to propel the mucus towards its mouth located in between all the arms. It doesn’t have a true stomach so the esophagus connects directly to the intestine. There are both male and female Crinoids (Feather Stars), and they reproduce by releasing sperm and eggs into the surrounding water.
Why do I think these are weird animals? If the description you just read about them doesn’t convince you, check out the video below.