This figure is part of Activity 6 Rotating snakes illusion. This picture shows a grid of 3x3 concentric patterns with a grid of 2x2 concentric patterns on top. Each concentric patterns consists of blocks of colour: blue, yellow, black and white. The circles all appear to be moving, some clockwise, some anticlockwise. If you focus on the centre on one of the circles, that group of patterns appears static.