The Phylum Phaeophyta are a multicellular group of stramenopiles. Organisms within this phylum include rockweeds, kelps, and brown algae. Brown algae range in sizes from microscopic to large giant kelps that can reach lengths of 100 meters. Their characteristic olive-brown color of brown algae is caused by the carotenoid pigment fucoxanthin which masks the green of chlorophylls a and c. Brown algae is found, for the most part, along coastlines of high latitudes such as the western North Atlantic Ocean and the northeastern coast of North America.