Sponge cakes can be covered in fondant icing or butter cream icing, or just fresh fruit.
Novelty cakes;- all figurines and accompanying decorations are made from fondant icing, all edible.
Fruit cakes, traditionally are covered in marzipan (almond paste) with the choice of fondant or royal icing.
Any hand crafted floral decorations are made from a harder icing.