Giant Nudibranch, Dendronotus iris.
One of the largest of the nudibranchs, reaching up to twelve inches long, they are very distinctive. These fascinating nudibranch prey on Tube Dwelling Anemone on sandy bottoms by sliding up to them and slowly rising up like a cobra. They then pounce down rapidly and their head gets sucked down into the tube as the anemone retracts. They also swim, to evade threats and to relocate themselves, by undulating their body back and forth.