Brown algae vary in colour from olive green to various shades of brown depending upon the amount of the xanthophyll pigment:

Step-by-step solution

The members of Phaeophyceae or brown algae possess chlorophyll a, c, carotenoids and xanthophylls. They vary in colour from olive green to various shades of brown depending upon the amount of the xanthophyll pigment, fucoxanthin present in them. Food is stored as complex carbohydrates, which may be in the form of laminarin or mannitol.