Cerianthus filiformis is a species of tube-dwelling sea anemone in the family Cerianthidae.

C. filiformis resembles the sea anemone and has a stretched and muscularised body which can reach 35 cm.

Tube dwelling anemones such as C. filiformis live in a mucous tube that they secrete in soft sand or sediment, unlike more typical anemones whose muscular foot holds on to rock or coral.

C. filiformis feeds on all the small-sized and edible drifting food which pass within the reach of its tentacles.

It protects itself from predators by retracting back into the tube, which can reach up to 100 cm in length.