From brown algae come alginates or algin. They make water-based products  thicker, creamier, and more stable over extreme differences in temperature, ph, and time.
 
Beta Carotene, a natural pigment derived from green algae, is used as a  yellow-orange food coloring.

ASSIGNMENT

I want you to read the ingredient labels on things you have in your house to see how many of them contain seaweed.   I would like you to make a list, showing the Product name and what seaweed product was in it. For at least TWO of the products you must include the label from the package