Tide

keep beating. it only moves because you do.

be the heart — tap a rhythm and drive one red cell around its full lap

Blood makes a full lap of the body along a real figure eight, not a circle, because the loop to the lungs and the loop through the rest of the body both start and end at the heart, crossing there. It only moves because the heart keeps pushing it — stop the rhythm and the lap slows, coasts, and stalls, the way it would if a real heart stopped.

Concepts: circulation, biology.

An interactive you play with one thumb, on Wundr.