Brown algae, usually with 7-9 cm in diameter, thin and delicate. It has baloon shape and it's full of seawater when young, but becomes contorted, hollow and empty, and colapses with age. The characteristic color results from the predominance of fucoxanthin, despite the presence of other pigments, like Chlorophyll a and c, beta-carotene and others xanthophylls. Usually it's attaches itself to hard surfaces, such as rocks or shells.