The first thing you will need for an earthworm terrarium is a vase or anything that is best for its surroundings. An earthworm needs moist dirt and some dead leaves so it can feed on the minerals from the leaf and soil. A plant is important to have because if the plant is growing it shows that the worm is releasing its waste to fertilize the plants roots, thereby introducing a mutualistic relationship. First, we get a vase and fill it with the dirt, sand, and worms. Now you pour the sand and dirt in layers. Worms usually come out at night and feed on dead leaves, therefore we put a couple of dead leaves and tiny twigs into the vase. We then cover the vase with our paper towel and wrap it with a rubber band. The terrarium should be in a dark space for the worms.