- Kingdom: Animalia
- Phylum: Chordata
- Subphylum: Tunicata
- Class: Ascidiacea
- Order: Aplousobranchia
- Family: Clavelinidae
- Scientific name: Clavelina lepadiformis
- Norwegian: langhals-sekkedyr
This is a colonial sea squirt, although each individual is only attached together by a fine stolon, a root-like extension running between the base of each animal. The body is transparent and does not exceed a length of 4 cm. A fine white or cream-colored line runs along the body and forms a ring at the top. The light bulb sea squirts start to grow in late winter and are ready for reproduction in the summer. During a few hours they release a large number of larvae. These attach to the bottom and forms small buds which are the basis for next year's colony. During the fall the sea squirts disintegrate.
It sits on hard substrate on depths from the subtidal zone and down to a maximum depth of 50 meters.
This sea squirt is known from the Atlantic coasts of Europe, as far north as Norway, and from the Mediterranean, including the Adriatic Sea.