ligament
From ZooTerms (Dictionary of Invertebrate Zoology)
tissue between parts or segments.
ligament (noun; Latin ligare, to bind): 1. A band or sheet of tough, fibrous
2. (Bryozoa) Muscle fibers embedded in collagen with a tubular peritoneal envelope.
3. (Mollusca: Bivalvia) A horny, elastic band located above the hinge, causing the valves to open when the adductor muscles relax.