These creatures are tiny termites (3 mm. in height) but the nests/mounds they build are tall and tough, which can withstand the rough weather as well as attacks from predators. Because of their characteristic castle-like mounds that they construct, these insects are known as Cathedral termites and are considered as remarkable engineers of the insect world.
By comparison we can get an idea of the height.
These are inhabitants of northern parts of Australia and their huge mounds, which often reach 6 to 8 meters in height, are frequently seen in the dry plains of northwest Australia. These are one of the tallest non-human animal structures in the world. The scientific name of these termites is Nasutitermes triodiae, also known as spinifex termites
They build these mounds with mud, plant parts mixed with termite saliva and faeces. These are built without any blue-print or any co-coordinator. These cathedrals have elaborate ventilation and cooling systems, different chambers for food storage, for fungal gardens and nursery for eggs and a chamber for the queen that produces eggs.
This structure is porous and the walls are filled with tiny holes for ventilation. The main nest or the living quarters are at the g round level or below it. These living chambers are separated by thin walls. The mound has a central chimney with a network of tunnels around it. Air flows through the porous walls to the central chimney. The fresh air mixes with the warm air of the mound, which gets cooled and sinks to the bottom. So the nest below gets fresh, cool air. This facilitates a constant circulation and helps keep the air inside the nest relatively cooler while the temperatures outside (in the arid northwest Australia) are raging high.
Each mound houses millions of termites. They have got caste system of workers, soldiers and king and queen termites. From the base of the mound there are long foraging tunnels. The workers reach to the surrounding plants and shrubs and collect food for the nest. These termites ‘farm’ fungal colonies and the fungus-termites have a symbiotic relationship.
These mud mounds are quite strong, but a heavy downpour can destroy around one third of the mound. However, in the dry, arid areas of northwest Australia, these nests last for 50 or more years.
If any part of the mound is broken, then within no time the worker termites are at the site, with their mouths full of soil to repair the damage. And the soldier termites also rush to defend the colony. The soldiers use chemical warfare while fighting the predators.
A video about these Cathedral termites by Sir Richard Attenborough can be found here.