Galls are abnormal growths that form on plants in response to insect activity or other environmental stressors. They can vary in size, shape, and color, and are often caused by the release of chemicals by the insect or plant in response to the irritation. Galls can be harmful to the plant if they disrupt normal growth patterns or block nutrient flow, but they can also provide protection for the insect that caused them. Overall, galls are a fascinating example of the complex interactions between plants and insects in the natural world.