This piece doesn't look at all like the rock I bought--the rock that I found this among was small, round, smooth pebbles...about 1/8th the size of this object that I found.
Looks like a broken piece of natural rock that has a couple flakes taken off the "blade" most likely due to friction with other rocks. There doesn't seem to be any intentional work done. Lots of times you'll get a delivery of stone with different sized rocks. That not uncommon. Good luck n happy hunting!