Tube-dwelling anemone
（重定向自Ceriantharia）
Tube-dwelling anemones or ceriantharians look very similar to sea anemones, but belong to an entirely different subclass of anthozoans. They are solitary, living buried in soft sediments. Tube anemones live and can withdraw into tubes, which are made of a fibrous material, which is made from secreted mucus and threads of nematocyst-like organelles, known as ptychocysts.