Agar or agar agar is a gelatinous substance chiefly used as a solid substrate to contain culture medium for microbiological work. It is an unbranched polysaccharide obtained from the cell membranes of some species of red algae, primarily from the genuses Gelidium and Gracilaria, or seaweed (Sphaerococcus euchema). Commercially it's derived primarily from Gelidium amansii. Agar can be used as a laxative, a vegetarian gelatin substitute, a thickener for soups, in jellies, ice cream and Japanese… (More on Agar)