Volvox

Just another tiny algae, Volvox form globe-like colonies by clinging together in a matrix, tails pointing outward. Through coordinated flapping, these body cells propel the colony through the water like a rolling ball. Inside the busy matrix layer, separate reproductive cells have no tail at all. They divide themselves, and divide again, eventually forming daughter colonies - tails pointed in. When the daughter colony is ready to leave the mother ship, they flip around, tails-out. The outer matrix dissolves momentarily, and the daughters roll out.