An Athenian allotment machine: a stone slab with rows of slots and a tube, used to select jurors and officials by lot.
In more detail
Citizens' identity tablets were placed in the slots, and black and white balls released through the tube decided which rows were chosen. Fragments found in the Agora excavations were recognised as allotment machines by Sterling Dow, using a description in Aristotle's Constitution of Athens. How the devices worked is reconstructed from fragments and that text.