What if blue whales grew mechanical limbs and rebuilt the landscape

In the deep open ocean, a pod of enormous blue whales grow articulated mechanical limbs and begin rebuilding the surrounding landscape. Gears, joints, tools, and moving material interact with convincing weight and purpose. Sun shafts, bubbles, plankton, and distant divers establish their scale. Follow the nearest set of limbs at work, then reveal many others rebuilding in coordination.