This would be an invasive species which is not native to the environment. It can cause harm either because it over grows (if it's a plant.) Or if it's an animal, it will reproduce and most likely take over the environment. This is because it feels the need to compete for materials, but ends either taking most or all of it. Which then ruins the food chain depending on it's diet. If it's eating a plant, then other animals that eat that plant no longer have any food. And vice versa if it's feeding on animals. Other predators, no longer have their food.
In the natural world, limiting factors like the availability of food, water, shelter and space can change animal and plant populations. Other limiting factors, like competition for resources, predation and disease can also impact populations.
Answer:
"*Because the lymphatic system collects excess tissue fluid, if it were not working, swelling (edema) would occur in the tissues. The thymus cleanses the blood from the cardiovascular system of cellular debris and bacteria."