Even the strongest human-made glue tends to fail when you dunk it underwater. Purdue researchers, however, think they have a simple solution to this: imitate nature. They've developed a polymer adhesive that's based on the proteins mussels use to cling to rocks. The team's synthetic creation takes advantage of compounds inside the proteins' amino acids to bind directly to an intended surface, rather than interacting with water on the surface. The result is a material that not only outperforms the glue you see in the hardware store, but is 17 times stronger than the shellfish's own adhesive -- and that has scientists scratching their heads.