Poison arrows and bone utensils in late Pleistocene eastern Africa: evidence from Kuumbi Cave, Zanzibar. Four of the projectile point fragments recovered from Kuumbi Cave: A, C, and G impact fractures; B and D possible retrieval cut marks; E rounded tip; F post-depositional fracture revealing bone surface; H change in surface appearance.

Poison arrows and bone utensils in late Pleistocene eastern Africa: evidence from Kuumbi Cave, Zanzibar. Four of the projectile point fragments recovered from Kuumbi Cave: A, C, and G impact fractures; B and D possible retrieval cut marks; E rounded tip; F post-depositional fracture revealing bone surface; H change in surface appearance.
http://www.tandfonline.com/doi/full/10.1080/0067270X.2016.1173302