Eulalia clavigera is a species of polychaete worm in the family Phyllodocidae, native to the coasts around Britain, through Western France, and to the Iberian Peninsula.

Before the 1990s, E. viridis was thought to have a wide range in the northeastern Atlantic including the waters around the United Kingdom, but morphological and biochemical studies led to the southern populations being recognised as a separate species E. clavigera, part of a species complex with E.

[2] This means that the distribution of E. clavigera is not well understood, with references in the literature referring to E viridis possibly being misapplied; however, E. clavigera is present around the coasts of Britain and southwards to France and the Iberian Peninsula, and possibly into the Mediterranean Sea.

It typically lives in crevices, under stones, among the holdfasts of large seaweeds and among mussels and barnacles.

[2] Eulalia clavigera is predominantly a scavenger and feeds on dead or damaged invertebrates such as barnacles and mussels.