The stringy, gooey material that some snails use to protect their developing eggs could one day inspire a new class of synthetic ligaments for joints. The meter-long egg strands secreted by the channeled whelk snail are often found washed up on the beaches; because of their resemblance to strings of pearls, they are known as mermaid necklaces.
Mermaid necklaces can absorb strong shocks and have a triple helical, rubbery structure that lets them withstand strong wave action without rupturing. The bonds that hold together a necklace's triple helices begin to break as the elastic material is pulled apart. After being stretched to its limit, a necklace doesn't instantly snap back like a rubber band. Instead, the broken bonds that held together the triple helices gradually reconstitute, slowly returning the mermaid necklace to its starting length.
A synthetic elastic that harnessed the necklace's high shock absorption could be used to create self-healing, durable ligaments and tendons in human joints and limbs. Unlike spider silk and other tough materials, mermaid necklaces' proteins can self-assemble, which should make them much easier to produce in large batches.