is a small, segmented, tube-dwelling infaunal polychaete belonging to the family Spionidae
(Levin 1984a, Bridges and Heppel 1996). The head is conspicuous, conical in shape, with four eyes, two banded gills and a pair of coiling, tentacle-like feeding palps. Each body segment is equipped with paired, paddle-like setose parapodia that are less robust than in many polychaetes. Individuals are typically reddish-brown and slightly transluscent, with dark green-brown gill bands (Weiss 1995).The mucoid sediment tubes occupied by S. benedicti
are soft and gray and occur at and just below the sediment-water interface (Weiss 1995).