Answer:
An ecosystem I would choose is a pond. Some living things in a pond could be frogs, flies, worms, and fishes. Some non-living things could be lily-pads, flowers, mud and grass. Frogs could eat the flies. But if the flies leave this pond, and don't come back the frogs could die. If the worms die, the grass and flowers may not grow. Because worms are decomposers and play a big role to help the plants.
Step-by-step explanation:
Because I said so. Hope this helps lol