Agar-agar is a jelly-like substance. Unlike Gelatin, it is made of algae and not animal skin and bones. It sets at room temperature and won't melt at warm temperatures. It's mainly sold in 3 forms: powder, flakes or blocks. It has no taste, no odor and no color, which makes it pretty convenient to use. Agar-agar may have been discovered in Japan by Mino Tarozaemon, who according to legend, was said to have discarded surplus seaweed soup and noticed that it gelled later after a winter night's freezing.