Juergens' research aroused interest in the media, but has been criticised. Walter R. Tschinkel, a biologist at Florida State University who also researched the fairy circles, remarked that Juergens, "has made the common scientific error of confusing correlation (even very strong correlation) with causation." Previously, Tschinkel had searched for harvester termites without success. Juergens responded that sand termites differ from harvester termites and live deep beneath the circle; they do not create mounds or nests above ground, and they leave no tracks in the sand. In such respects the sand termite is unusually inconspicuous in its activities.