Their mounds look rather like tombstones. They are some 5-8 ft tall, very thin East-West (about 4 inches) and long North-South (2-3 feet). They are aligned like this to reduce the impact of the sun on the nests.
The termites are known as magnetic termites or compass termites because of this alignment. But the worker termites are blind, so how do they actually manage the alignment? By sensing the sun’s heat? No…
Recently, Mad Scientists ™ experimented by using magnets to distort the local compass direction. The termites then obediently built a nest aligned with the magnets rather than with true North. So they really are magnetic termites, doing magnetic sensing! Way cool!
The nests I saw were in Litchfield National Park. There is a large array of the tombstone like mounds in a small area, looking like a grave yard. This made me wonder if the name “Litchfield” might have come from “Lich Field”, but no, it turns the park name comes from a famous Northern Territory pioneer.