The Tube anemone (Cerianthus membranaceus), is a tube dwelling, marine anemone having a long cylindrical body of which a larger part is bored into the sandy or muddy substrate. In case of risk or danger it can retract its entire body into the tube. A small portion of the tube sticks out, from which tentacles fan out to collect food, like krill, small fish or other fine, but always meaty nutrients. The tentacles are fluorescent, with colors in variable shades of purple, violet, red, orange, blue and green.Tube anemones much resemble sea anemones, but the two belong to entirely different subclasses.