Clava multicornis

Clava multicornis is a species of athecate hydroid belonging to the family Hydractiniidae. It is currently the only accepted member of the genus Clava.

This is a coastal species found on both sides of the north Atlantic. It appears as a group of pink or red "stems" (hydrocauli), up to 25 mm tall, with distinctively clubbed ends bearing thread-like tentacles. It can be found on rocks but is most often seen attached to seaweed, especially brown seaweeds such as Ascophyllum and Fucus.