To meet their structural needs, some ants build huge hills out of sticks and dirt. These mounds often extend underground to vast tunnels and galleries. Inside the hill, ants bring food to their queen. She lays eggs which other ants care for in nurseries. Some ant species live on fungi which they plant, grow, and take care of in underground galleries.
Beavers like to swim around in ponds and lakes.
If there isn't a pond or lake available, beavers have the structural know-how to build their own. They use the same methods to build dams as we do. Beavers make a dam foundation by wedging large branches or logs into the bottom of the stream bed. Next they add layers of branches, held together with mud, rocks, and loose vegetation. A coating of mud seals the structure.