The Mexican Truffle?
Cuitlacoche - pronounced as QUEET-la-coh-chay is a stone-shaped fungus that turns into a gunky, tar-like mush when cooked.
It grows when a drop of rain seeps into a husk of corn. The moisture rots between the kernels and produces a fungus. Makes for yummy tacos or a flavorful omelet. For full article See: https://www.npr.org/templates/story/story.php?storyId=111789560