Why do we have a special plate for Passover
Displaying a "Seder plate" at the Passover Seder meals is a custom described in all Hagadahs. From Wikipedia: Each of the six items arranged on the plate has special significance to the retelling of the story of Passover—the exodus from Egypt—which is the focus of this ritual meal. A seventh symbolic item used during the meal—the three matzos—is not considered part of the Seder plate proper.
There are endless of reasons behind each item on the seder plate. I would advise you to check it up in a hagada. Besdies for the simple reasons there are other reasons on a kabbalistic scale too.
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