In double boiler melt 16 large marshmallows. Stir in 1 cup milk. Pour over large package lime Jello and stir until dissolved. Add 8 ounce package cream cheese, softened. Beat with mixture. Stir in #2 can crushed pineapple, undrained. Add 4 ounce Cool Whip and 2/3 cup mayonnaise. Pour into Jello mold. Chill until firm, about 3 hours.