Spirorbis is a genus of very small (2-5mm) polychaete worms, usually with a white coiled shell.

They live in the lower intertidal and subtidal zones on the rocky shore. They may be attached to seaweeds, rocks, shells or other hard substrates.

As filter feeders they use the gills to filter plankton out of seawater.

This spiral worm can be found attached to almost any hard surface and can be a real nuisance when attached to aquarium glass!