Movie S2. High-magnification imaging of beating cilia on the surface of a P. damicornis explant. The white contour is the edge of the coral tissue. Above it, cilia are clearly visible and beat mostly toward the right. The cilia beat rate was ∼16 Hz. The video was captured by phase-contrast microscopy using a 100× objective at 1,000 frames per second and is played back 33 times slower than real time.