Oh, sea cucumbers! What can't you do? Besides accept my love, I mean?
Researchers have developed a two-compound polymer that goes from "rigid to floppy when soaked in water." They hope to use the material in brain implants. Another version, which switches between hard and floppy when hit with an electric shock—ahem—might be used to develop clothing that can turn into uncomfortably chafing armor.
From New Scientist:
Sea cucumber skin can become more than 10 times stiffer in this way, but the new material can go further – softening by more than 2500 times. Simply soaking the transparent material in warm water for 15 minutes is all it takes to complete the transformation. After drying out it is identical to its original rigid state.
Floppy when wet: Sea cucumber inspires new plastic [Technology.NewScientist.com] (Thanks, Nathan!)