When worms burrow through dirt, they break it apart and create air pockets that help roots spread. Planting tomato, green bean, and radish seeds in six pots — three with ten earthworms, three worm-free — puts this directly to the test. Water all pots equally, give them the same sunlight, and measure after eight days. Every plant type grown with earthworms ends up taller than its worm-free counterpart, showing how quickly worms can change what soil does for a growing plant.