This is a real witch’s cauldron, coated in a black tarry substance. It reportedly exploded when some Cornish witches were making a powerful potion by the sea, in order to invoke a spirit. One account describes how, when ‘it was realised that the volume of the smoke was reaching unprecedented proportions … they lost their nerve and panicked and fled the spot as best they could.’ When their friends visited the site, all they found was this damaged cauldron.