Ants are found in large colonies under the ground. There are more than 12,000 species of ants all over the world. When ants build a nest, they burrow into the ground or under rocks or a fallen tree. They expand their nest to make room for new ants. As nests grow, they can become large and complex, consisting of inter-connected corridors and chambers. They hide their underground nest’s entrance with hills of dirt. This protects their queen, other worker ants, baby ants and their food supply.