1. chlorophyll-bearing organisms lacking true stems, roots, or leaves
2. a brown pigment of the algae
3. any one of certain large, tough, brown seaweeds; the source of potassium, iodine, algin, and sodium carbonate
4. a red pigment found in red algae and in a few cyanobacteria
a, fucoxanthin b, kelp c, algae d, phycoerythrin