These resemble anemones, although they can be distinguished by their non-retractable
tentacles. Moreover, they are not attached by a single foot but live in a self-secreted
tube, whose support requires a layer of not too rough sand, 15-20 cm thick. Ceriantharia
feed on finely ground mussels, fish, shrimps, or brine shrimps. Certain species
can sometimes be found in the aquarium trade, although their name is often unknown
or incorrect. Height: 20-30 cm.