This is a bone thin section made from an approximately 4000 years old human cranial bone, viewed under polarized light. This kind of black spots are everywhere on the thin section. Do not seem to be constrained by osteons. Do not seem to be Wedl-type tunnels as well because they have distributed well into the bone's interior. Do not seem to be non-Wedl MFD as well, since there is no hypermineralized cuff around it. Any help identifying these is much appreciated.