Kuki Waterstone/Alamy A non-toxic underwater glue that is inspired by barnacles and made from silk is stronger than most synthetic adhesives. Barnacles and mussels use a clever combination of factors to stick to rocks or to the side of boats. In particular, they layer protein filaments into a cement-like structure that is cross-linked for extra strength. These filaments – called byssus – form into polymers on the surface the shellfish wants to cling to. In nature, they are then strengthened by iron-containing complex molecules. Fiorenzo Omenetto at Tufts University in Massachusetts and his colleagues sought to replicate that using silk from silk worms.