Geological horror. You find a geode and crack it open and the crystal lining its walls is human blood that can’t be genetically matched to anyone. You find a human skeleton but every one of the bones is made from rock, a rock that you know can’t be whittled into those shapes. You find layers of clay and loam that sport ancient fossils at the top and the still-rotting corpses of modern animals at the bottom.
This reminds me of the blood river in Antarctica. For like a century scientists had no clue why this river looked like, acted like, and felt exactly like blood. Turns out it’s just really high in iron.
That’s so epic I love it when rocks and water and such look like blood