The great leap backward

The fact that the ingot had to be cast into fish form, otherwise people wouldn't put it in their pots? See e.g. the attempt with the lotus flower shape:

> The research group distributed an iron disc to women in the village, asking them to place the disc in their pot while making soup or boiling water. The women were reluctant to use the chunk of iron while cooking, and "almost no one used it". [...] Charles and others distributed iron ingots in the shape of a lotus flower, but that was also rejected by the villagers. During discussions with village elders, Charles learned about a fish species deemed a symbol of good luck, health, and happiness in local folklore. The group created fish-shaped iron ingots, which were received more positively by the villagers and led to immediate increases in blood iron levels amongst the villagers, and anemia was virtually eliminated. Charles would later state that "You can have the best treatment in the world, but if people won’t use it, it won't matter."