Abstract: Comprising a long and flexible body (1), which defines two ends (2,3), having fixing means of the female type (4) and the male type (5), on both ends, characterized in that the long and flexible body (1) is lengthwise twisted on itself and is made of such a material as cellulose (7) or a by-product thereof, and/or the fixing means (4,5) are made of a biodegradable plastic material.