Category: Algae
Phylum: Heterokontophyta
Class: Phaeophyceae
Family: Desmarestiaceae

Notes
Widely distributed in polar to warm-temperate seas. Dominant and stand-forming in Antarctica and some parts of the Arctic. plant is erect,cylindrical (or slightly tapering), flattened or strap shaped, simple or branched, may be several metres high, annual or perennial, usually epilithic (grows on other plants). Sap of the annual species contains sulfuric acid, pH may be as low as 1. Plants left on rocks in the sun can etch their shape onto the rocks, when collected must be kept separated from other seaweeds or they will destroy them.
Can be used to make sour pickles.

References
http://www.algaebase.org/search/genus/detail/?genus_id=56&-session=abv4:8B502C6B1d6be38A5COhvTF07C1A (accessed 06/12/10)