Codium

Codium is a genus of about 143 species of edible green seaweed found in tropical to temperate intertidal and subtidal waters worldwide, though not in polar regions. Its spongy structure is built from siphons, single tubular multinucleated cells with swollen ends called utricles, forming mat-like, spherical or branched growth forms; South Korea leads the world in harvesting and consuming it, gathering roughly 4,000 metric tons a year, while some species such as Codium fragile have become invasive through marine shipping.