Antler fungus exists. If you go out to the forest and eat 20 pounds of rotted leaves and soil, then lay on your back with your mouth open during a rainstorm, this will grow right out of you overnight.
It is an actual mushroom I captured from a photo that came up when I did a Google for 'antler fungus'. This was after a discussion on (possible) hazards of working with antler. I don't know anything about it. But it is weird, fer certain, fer sure. From the leaves and stuff I cropped out, I would estimate it is almost one foot tall.