A variant of Tim Hutton's Mutually-Catalytic Spots system, in which small spots (highlighted in red) follow the contours of large spots, creating "pinwheels". Small spots in the interior of large spots travel clockwise, while small spots on the exterior travel counter-clockwise.
by Tim Hutton
Two coupled Gray-Scott systems. The large spots can only replicate when full of small red spots. Likewise the red spots can only grow inside the large spots - outside of the large spots they die out. The large spots usually inherit their small spots when they replicate - those that don't will no longer replicate. In the starting pattern only the central spot is seeded with small spots. The other two spots don't replicate at all.