- Kingdom: Animalia
- Phylum: Cnidaria
- Class: Hydrozoa
- Subclass: Hydroidolina
- Order: Leptothecata
- Family: Haleciidae
- Scientific name: Halecium halecium
- Norwegian: liten sjøgran
Hydroid stage: Looks like a feather with numerous branches defining a plane. Each branch has a separate joint to the main stem. The hydroids grow on both sides of the regularly spaced branches alternating along the stem. The colony may grow to a height of 25 cm. Sometimes it has several stems growing from the fibrous base.
Medusa stage: No information.
It is usually found on depths between 20 and 100 meters, preferably on rocky substrate.
The Herring-bone hydroid is record in the Atlantic Ocean, from Spitzbergen to South-AFrica, as well as from parts of the Pacific Ocean.