A machine or tool used for separating seeds from a grain can be called a thresher. The mechanical thresher was invented in the 18th century.
Threshers have simplified the work of agriculture, automating a job that humans once spent tedious hours doing. A combine is an even more efficient machine, combining a thresher and a harvester—it picks the grain and separates its seeds. A scythe is a curved knife used for hand threshing, and the thresher shark gets its name from a resemblance to this tool.