What are the distinguishing characteristics of Porifera?
"A Guide for the Study of Animals" by Worrallo Whitney
The phylum Porifera or Spongiae includes the simplest of the Metazoa or multicellular animals.
"Freshwater Sponges, Hydroids & Polyzoa" by Nelson Annandale
The sponges have received the name of Porifera, on account of the structure above described.
"Stories of the Universe: Animal Life" by B. Lindsay