N. robusta is found between Alaska and southern California in the middle of the intertidal zone.

This worm makes its thick tubes out of clay particles, and is most commonly found under rocks that sit on either mud or muddy sand. The worms attach their tubes to the bottom of the rocks.

In the field these worms may be quite common.  On Portland Island either worms, or their empty tubes,  were found under nearly  every rock in the mid-intertidal zone.

Hairy gilled worms in the remains of their burrows. Note the sea cucumber in the upper right portion of this photo.