Gnamma holes, one guarded, one not. There was no plaque to say what the metal contraption was really for. Clearly it would not deter a child let alone an adult (not that it seemed to be drinkable, though if you were despereate enough it would get you by), nor small animals, and seemed to enable room for roos to duck in and get a drink. there were no fittings at the top of the metal guard to suggest it was for anything more sophisitcated. Besides, the gnamma hole was not overly deep – about waist level. The only possibility was that it would deter the more ungainly, less agile and feral camels from using this limited source of water and depriving native animals. However, the metal guard was irrelevant, given that the neighbouring gnamma hole was unguarded (and there were two guarded gnamma holes and several others unguarded further along), so what was the point?