Termite Research
A distinctive feature of these mounds is the northward tilt of the spire. At our study site in northern Namibia, this tilt is about 19 degrees on average, which corresponds to the average zenith angle of the sun (and to the latitude). The spire's northward tilt is probably due to termites building more avidly on the warmer north-facing surface of the mound (remember that Namibia is in the southern hemisphere). You can read more about this, including a video of how it happens, here.