Quinoa, a grain-like crop grown in South America, is not one of the grains considered chametz (wheat, barley, rye, oats, spelt, or their derivatives). Some medieval Ashkenazi rabbis ruled that kitniyot (legumes) could not be eaten during Passover because they could be confused with chametz products. Some authorities consider quinoa to be kitniyot, while others do not.
The Hebrew word seder means “order” and refers to the religious service and festive meal observed in Jewish households on Pesach.
The shank bone symbolizes the paschal offering brought to the Temple in Jerusalem in ancient times.