Small, cylindrical, sycon-type sponges common in shallow marine waters. Sycon-type sponges are intermediate-in terms of morphological complexity-between the simplest bag-like sponges and the intricate architecture of the leuconoid sponges. The phylum Porifera can be viewed as occupying middle-ground between the colonial flagellates and the true multicellular animals. Evolutionarily, however, they probably represent a dead-end. Size range is 1/2" to 3/" in length.