Fossilization

An orange Elephant Ear sponge (Agelas clathrodes) at the Florida Keys National Maritime Sanctuary (photo from NASA)

The sponges or poriferans (from the Greek poros "pore" and ferro "to bear") are animals of the Kingdom Animalia, Phylum Porifera. They are primitive, sessile (coach potatoes that are not able to move about), mostly marine, water dwelling filter feeders that pump water through their bodies to filter out particles of food matter. Sponges are among the simplest of animals that lack true tissues such as muscles, nerves, and internal organs. Their similarity to colonial choanoflagellates (protozoans) shows the probable evolutionary leap from unicellular to multicellular organisms. Since I am a multicellular organism, the sponges that appeared in the Precambrian are my most ancient and primitive ancestors. Uncle Sponge Bob shown above is a likely ancestor of all animals that were to follow. The fossil record of sponges is not abundant because my sponge ancestors possessed soft bodies. The sponges live on today, with more than 5,000 extant species known. Sponges are found attached to surfaces anywhere from the intertidal zones to miles deep in the ocean.