Fucus spiralis is an intertidal brown seaweed, found on the high shore that grows up to 40 cm long, without air bladders and lives for up to 4 years. It can easily be confused with F. ceranoides or with bladderless forms of F. vesiculosus.

This species can tolerate a high level of desiccation. Fronds have a characteristic ridge along the edge of the receptacles. Is one of our commonest and most familiar seaweeds. It typically forms a zone high on rocky shores.

Well grown plants are usually easily recognisable by the flattened, twisted, dichotomously branched thallus, lacking bladders, and the large, oval receptacles at the frond tips, each receptacle being surrounded by a narrow rim of vegetative frond. However, younger plants are not always so easy to identify.