Brown algae are eukaryotic algae with a food reserve in the form of laminarin and a lot of chlorophyll a, chlorophyll c, fucoxanthin, and phycocolloids.
Brown algae have chlorophyll a, chlorophyll c, and carotenoids as photosynthetic pigments.
The brown color of algae is caused by a high concentration of xanthophyll called Fucoxanthin.