The shank bone on the Seder plate is called the zeroa, also transliterated as zeroah or זרוע. It represents the roasted Passover lamb sacrificed in ancient Jerusalem during the period of the Temple.
The zeroa is one of the symbolic foods arranged on the Seder plate. In many Jewish traditions it is a lamb shank bone, although some families use a chicken wing or neck instead. Vegetarian households may substitute a roasted beet, drawing on rabbinic discussion that permits a non-meat symbol.
The zeroa is generally displayed rather than eaten during the Seder. That practice emphasizes its role as a reminder of the korban Pesach, the Passover offering, rather than an actual sacrifice. It is often confused with the beitzah, the roasted egg on the plate. The egg symbolizes another ancient festival offering and mourning for the destruction of the Temple; it is not the shank-bone symbol.