If you have dived into the sea, you've probably seen a chubby and elongated creature known as sea cucumber. This small marine animal, which in some regions is considered a gastronomic delight with medicinal properties, has a soft and supple skin can harden in seconds, turning your dermis in armor. The sea cucumber when it feels threatened undergoes an enzymatic reaction, causing the fiber proteins of his skin are made to form a rigid structure. Another enzymatic reaction breaks these bonds causing the skin to become soft again. Researchers at Case Western Reserve University in Ohio (USA) were inspired by this animal in 2008 to develop polymer nanocomposites with cellulose nanofibers with same characteristics. One of the applications which have achieved major advances has been in the area of health, specifically in the field of smart brain implants useful in patients with Parkinson's or spinal cord injuries.