From Fallen London Wiki (Staging)
"625 for 2 actions: Build on the Human Ribcage then Break down your (Skeleton Type) for parts (Human Ribcage); if your Dangerous is below 250 you will occasionally receive 312 Bone Fragments instead. Alternatively, any skeleton may be broken down to convert its Value into either hints or fragments."
How though? I only got 125 when I did this, did this action get nerfed?