Japanese wireweed

Sargassum muticum is a large, yellowish-brown or olive-brown seaweed that can be distinguished from most other Pacific coast seaweeds by its small, spherical float bladders. It grows on rocks, shells or other hard objects, attached by a stout, spongy holdfast. The lowest part of the stalk just above the holdfast is sometimes divided into a few main stems, and gives off several flat, blade-like leaves up to 10 cm long. Above that, the main stems branch repeatedly to form a bushy plant that is often 1-2 m long, with a maximum length of about 10 m. The branches bear small leaves, club-shaped reproductive bodies, and the spherical float bladders. The leaves are up to 2 cm long and either smooth-edged or toothed (the latter resembling small holly leaves).