Did you know that our heart doesn't actually pump? It actually twists itself to circulate blood. The heart circulates blood as if it were wringing a towel. The bottom twists in a counterclockwise direction while the top twists clockwise. On the right is the team’s model of the heart, showing tube-like pneumatic artificial muscles (PAMs) that mimic the heart’s striated muscle fibers. Credit: Harvard’s Wyss Institute and SEAS.