One crisp winter day in 2004, Uran Pelushi was walking along the banks of the Vivo, a creek in the Seggiano Valley in southern Tuscany. Unexpectedly, he noticed an object jutting from the leaf-covered earth.

At first, it resembled one of the many charcoal-colored tuff rocks that cover the ground in the area. But as he cleared away the weeds around it, a more complex structure started to emerge.