Cellophane noodles, also known as bean thread, harusame or glass noodles, are fine, dry transparent noodles made from green mung beans paste (starch). They are used in Chinese, Thai and other Asian cuisines.
Cellophane Noodles. Also known as bead threads and slippery noodles, cellophane noodles are made from the starch of mung beans, which are most familiar to us as sprouts. Cellophane noodles are translucent in their dried form, but once softened in hot water and cooked, they become gelatinous and transparent. Since they have little or no taste and will absorb the flavors of the ingredients that are cooked with, these noodles are prized mainly for their texture.
Cellophane noodles are sold in 1.8- ounce and 3.5-ounce packages.
(Wheat Foods Council)