COMMONWEALTH MFG-Basketry Sea Grass. Seagrass is a twine-like material that has been twisted to resemble rope. It is made of a natural straw-like product which is variegated green and tan in color. The green color will turn brown with age. It can be dyed. It is used for seat weaving some furniture and basketry. This package contains 1lb of #1 3x3-1/2mm Sea Grass (approximately 210ft). Imported.