Specialized projectile weapons as well have been found at various sites in Middle Stone Age Africa, including bone and stone arrowheads at South African sites such as Sibudu Cave (along with an early bone needle also found at Sibudu) dating approximately 72,000-60,000 years ago on some of which poisons may have been used, and bone harpoons at the Central African site of Katanda dating to about 90,000 years ago. Evidence also exists for the systematic heat treating of silcrete stone to increased its flake-ability for the purpose of toolmaking, beginning approximately 164,000 years ago at the South African site of Pinnacle Point and becoming common there for the creation of microlithic tools at about 72,000 years ago.