In a large mixing bowl, combine the mini marshmallows, sliced strawberries, sliced bananas, and crushed pineapple. Gently fold the ingredients together until well mixed.
Add the whipped topping to the fruit mixture and fold it in carefully to maintain the fluffiness.
If using, stir in the chopped walnuts for added crunch.
Drizzle the chocolate syrup over the salad and gently mix to combine.
Transfer the salad to a serving dish or individual bowls.
Garnish with maraschino cherries on top.
Chill in the refrigerator for at least 1 hour before serving to allow the flavors to meld.