Creek-dwelling caddisfly larvae make themselves a case of stones to protect themselves from predators and weigh themselves down so they aren’t swept downstream. Gland under their chins work like a tape dispenser, producing a type of sticky silk that bonds the pebbles together. So far, humans have struggled to make a tape that bonds while wet, but these larvae have no trouble constructing their case entirely underwater. If scientists could mimic the silk, they might be able to repair things in other soggy spots—the human body, for example.