Phylum: Rhodophyta

C₁₄H₂₄O₉

Agar-agar is a jelly-like substance, obtained from algae. Agar forms the supporting structure in the cell walls of certain species of algae. These algae are known as agarophytes, and belong to the Rhodophyta (red algae) phylum. 

A substrate for microbiological work, a vegetarian substitute for gelatin, a thickener for soups, in fruit preserves, ice cream, and other desserts, as a clarifying agent in brewing, and for sizing paper and fabrics.