Sea sponges are among the longest present lifeforms on earth, they are multi cellular organisms which are found in the sea, although fresh water ones are also present. They filter feed, waiting for debris or small plankton to pass by or by floating through the water. They have existed since the Cambrian period, making their fossil record over 550 million years old, with some studies suggesting they were present before this period. they vary widely in shape and colour and many other attributes. Like most animals, only their hard secretions are fossilised and sometimes in excellent detail.