Since the 1800s, explorers and hunters in the Siberian taiga have reported encountering strange copper "cauldrons", half buried in the ground. Although temperatures in this region are some of the coldest in the world, hunters who seek shelter within the copper domes find it pleasantly warm. However, many who enter the cauldrons end up dying of an unexplained illness that causes confusion and dizziness. What are these copper cauldrons and what is their origin?

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