There are a few main passover symbols that can be placed on the seder plate, but not all of them are required. A few examples of the passover symbols are vegetables (Karpas), shank bone (zeroa) or roasted beet, matzah, hard boiled egg (baytzah), charoset, bitter herbs (Maror), bitter vegetables (Hazeret), or oranges (optional). The reasons behind placing the matzah and the bitter herbs stand out the most among others.
each item in itself
holds a purpose,