Sea sponges are the simplest of multi-cellular animals. They live in the sea bottom and attach themselves to something solid. They come in all shapes, sizes and colours and are found in every ocean in the world, particularly the antarctic. They can survive in shallow water or in the deepst depths of the ocean and even in sea caves, where there is no light. They have no real organs and their body tissue consists of fibre-like protein, just like a bath sponge. Sea sponges feed by filtering tiny food particles from the water.

Sea sponges are hermaphrodites and can produce sperm or eggs, as required. Fertilized eggs become larvae, that swim away to colonize new areas.