Yharnam Stone is a Key Item in Bloodborne.
Yharnam Stone Usage
- No further use than proving your accomplishment.
- Unlocks Ritual Blood (4) from bath messengers.
- Drops from Yharnam, Blood Queen of the Old Labyrinth
- Stays in your inventory when moving to NG+
- This item may also be there to represent the queen's immortality (Much like the Queenly Flesh dropped from Annalise). However unlike Annalise, Yharnam cannot be revived.
- One could reasonably assume that this is a so called Lithopedion, a calcified, unborn, dead fetus.