Also known as agar-agar, Ceylon moss, China grass, Japanese isinglass. A gelatinous, soluble fiber extracted from marine red algae (Phylum Rhodophyta), agar is used to thicken soups, drinks, puddings, and desserts. It's a vegan substitute for gelatin. Commercially available agar is most commonly derived from Gelidium amansii, Gracilaria spp., or Sphaerococcus spp., that are colloquially referred to as seaweeds. See also Gelatin.