This mortar and pestle is made of a fine grain wood, suitable for many grinding needs!
The history of the mortar & pestle, and its usage has been around for thousands of years, as it was one of the very few implements our ancestors relied upon to cook. 
Our predecessors had fire, sharpened rocks for cutting, vessels to contain their food, and, crucially, they had stones and wood to pound and grind it all.
Many kitchens in the modern world also used them to grind herbs and spices,smashing fibers and cells apart to fundamentally transform their texture and release their full aroma and flavor.