A sickle, or "zerria." Jesus Bernaola used this to cut grass and wheat (to be milled for bread) on the Caserio Beaskoa in Arteaga, Bizkaia.
The iron blade was angled backwards from the handle to allow a smooth cutting motion. The sickle has a wooden handle with a metal collar around where the blade is attached. The blade has a long tang that passes through the handle. The end of the tang is crimped over at the end.