Eupolymnia nebulosa is a species of sedentary marine polychaete worm in the family Terebellidae.

It builds a tube of slime under stones or large shells on soft substrates on the lower shore and down to depths of about 500 metres.

The soft body is up to seventeen centimeters long, broadest in the front, tapering, yellowish or orange with white markings.

There is a crown of numerous long, pinkish thread-like tentacles which writhe sinuously even when broken off.

[3] Eupolymnia nebulosa is found on soft substrates such as clay, silt, fine and coarse sand from the littoral zone down to about 500 metres.