Pōhaku (Stone)

Summary: 
Round stone.
Description: 

Volcanic Rock. Height: 4 3/4 inches, Circumference: 10 1/2 inches, Surface: Relatively smooth with several large holes, Color: Grey, Weight: 1 lb. 14.2 oz. Appears to have been the end of a large pestle which was broken. However exact use and origin are unknown.