Irradiated prawns. Prawns with a radiation symbol depicting irradiation of the food. This exposure to ionising radiation kills any harmful bacteria that may be present. Prawn is a general term for any of the larger shrimp-like Crustaceans. They belong to the order Decapoda. Typically they are transparent, only becoming pink once they have been cooked. The edible part of their body is the abdominal muscle that they use for swimming.