Jack's Reef pentagonal projectile point
Jacks Reef Pentagonal is the name for small (1" to 1 ½"), broad projectiles and specialized knives. They were named by William A. Ritchie based on examples recovered from the Point Peninsula Jack's Reef archaeological site in Onondaga County, New York.
Source: Wikipedia — Jack's Reef pentagonal projectile point (CC BY-SA 4.0)