They had found obsidian The tools are much smaller and more sophisticated than the older, teardrop-shaped stone tools found in the same area in southern Kenya.

Stone bowls. Hammer stones (as seen in Figure 12) were used as a percussion tool for making other kinds of stone tools. Stone bowls are made from various granular stones (see Figure 13). An artist may ...

The archaeologists uncovered almost 600 obsidian stone tools and identified the oldest known "workshop," the study says. Such workshops developed as tool-making evolved into a skill.