Place the cranberries and sugar in a blender or food processor. Blend until smooth, scraping down the sides as needed.
Drain the crushed pineapple in a colander, pressing on the fruit to extract as much liquid as possible. Add the cranberry mixture, crushed pineapple and mix to combine. Gently fold in the cocowhip and marshmallows.
Pour the mixture into a serving dish. Let sit for at least 6 hours and up to overnight. Top with pomegranate seeds. Enjoy!
